To begin with, the D6 space rules actually differ a bit from Star Wars D6. I'm not sure if it matters for this particular question (I haven't fully read through D6 Space), but it's worth being aware of.

This answer is based on the Second Edition, Revised and Expanded rules (Color Millennium Falcon cover; the most recent prior to D6 Space).

Basic Targetting

For ranged, the difficulty is based on the range to your target (page 88). Point-blank is Very Easy, medium range is Moderate, etc.

The actual distance defined as point-blank, medium, etc. varies from weapon to weapon. For example, a Bowcaster is listed as having a range of 3-10/30/50. This means that 0-3 meters is point-blank, 3-10 meters is short range, 10-30 meters is medium range, and 30-50 meters is long range.

For melee, the difficulty to hit is listed on the weapon (page 89). A vibro-ax is a moderate difficulty to hit with. A knife is a very easy difficulty.

Resisting Targets

Characters can use reaction skills to make themselves harder to hit (page 79). This is generally going to be either dodge, melee parry, or brawling parry.

When someone attacks you, but before you know if they hit, you can declare a reaction. This uses either one of your pre-declared actions or can be a new action (your choice). Multiple action penalties apply to the reaction, and if you make it a new action while you have other actions remaining the reaction adds to the multiple action penalty for those additional actions.

The reaction roll replaces your base target number to be hit. Even if it's lower. And it applies to all further attacks of that type in the round. A bad reaction roll can potentially be bad news (although the difficulties in ranged combat are generally pretty low to begin with).

The reaction skills are summarized on pages 89 and 90. Note that dodge is exclusively for ranged attacks and grenades. Ducking out of the way of a knife is brawling parry, not dodge.

Modifiers

There are a few modifiers that apply on top of reaction skill use.

Unarmed vs. Armed -- When armed, attacking or parrying against an unarmed opponent gains a static bonus (melee parry gets +5 vs. unarmed opponents, brawling parry grants armed opponents a +10 bonus). Just add this in when it's appropriate (page 90).

Cover -- Usually if you have cover from one person, you'll have it against everyone. When this isn't the case, you have a few options:

• Roll the dodge and cover separately. Keep track of both numbers and apply as appropriate.

• Roll the dodge during the first attack. During each attack impacted by cover, have the player roll his cover dice whenever he would otherwise be hit.

If the attacker beats the target number to hit the character (i.e. their dodge in most cases) but misses due to cover, they hit what the character was hiding behind. If it's something that can be damaged, they roll to damage the cover (page 93-94).

Full Reaction

The final piece to the reaction skill puzzle is full reactions. This represents going entirely on the defensive. A full reaction can be the only action taken in the round, but adds the base difficulty to hit to the reaction skill (page 90). Note that a full dodge precludes parrying (and vice versa).

Static Target Numbers

Static target numbers are actually the default in 1E; the ranges are shown on the tables in 2E, but generally, just use the high numbers to have the same as in 1E.

From 1st Ed rules:

Very Easy: 5
Easy 10
Moderate 15
Difficult 20
Very Difficult 30
Heroic 50+

If you want to have static TN's for opposed rolls, use dice x3 plus the pips.
*EG: 3d+2 would be (3x3)+2=11; 4d+0 would be 12, etc.

Other speedups from earlier editions

Reactions

Dodge, shields, and Parry can be allowed only as reactions - this makes all characters a little less adroit at defense, but is faster to play. Spend an action as a reaction, if made, the roll applies only to that one attack. Any rolls made after take the 1D penalty for multiple actions

Shields as a reaction: rather than angling shields as per 2E, simply roll shields at the time a hit comes in; if dodge+TN from Range or Dodge is greater than the to hit roll, then the shield's dice are applied.

No Initiative Rolls

Everyone declares actions; everyone rolls their first action - then, in descending order of roll, resolve each action (and make any reaction rolls needed). Then if anyone has second actions, repeat, and so on.

It's actually much quicker, but relies upon people's dice being visually distinct on the table. (It's also from 1E)

No scaling Tables

The 1E scaling is simpler... the following is an adaptation of it.

Shooting up a scale: (personal to walker/speeder; walker/speeder to starfighter; starfighter to capital)
Smaller rolls double on To hit;
larger rolls double on hull resistance and shields.

Shooting up two scales
Smaller rolls double to hit, but only 1/3 the damage (0-5d = 1d, 6d-8d rolls 2d, etc)
Larger rolls double on hull and shields, but only 1/3 the pilot or shield skill rolls on defense.

Shooting down one scale
Smaller rolls normally
Larger doubles damage rolls

Shooting down two scales
Smaller doubles dodge may rolls only 1/3 the dice to resist damage
Larger doubles damage rolls

Shooting down three scales
Smaller dies if hit. Dodge doubled
Larger kills on a hit, only rolls 1/3 the dice to hit.

No CP in play

Don't allow spending Character Points for bonus dice except when resisting damage. One less decision to make.

Ignore the pips

Treat Pips as just a placeholder to advancement. Ignore the +x when making rolls.

Borrowing from Star Wars Minaiture Battles...

A simplification used in the miniatures rules reduces things down to 1d6 for all rolls. THe score used is the same as the dice from the RPG. As in a 3d+1 blaster is rolled on 1d6+3 vs the target's dodge.

Note that the mechanics for damage need to be adjusted, as well.

Dam = Res : Stunned
Dam > Res : Wounded
Dam ≥ Res +3 : Incapacitated
Dam ≥ Res +6 : Mortal Wound
Dam ≥ Res +9 : dead.
note: this does not exactly replicate the core nor the SWMB table for same. It's harder to kill unless you open end 6s.