[RPG] Does the caster level of a spell-like ability satisfy prerequisites of item creation feats

By RAW an alchemist don't have a caster level, so he doesn't qualify for the requirements to take any crafting feats.

You can read more about it in this FAQ which states:

Is an alchemist a spellcaster for the purpose of crafting magic items other than potions? As written, no, alchemists are not spellcasters, and therefore can't select feats such as Craft Wondrous Item. The design team is aware that this creates some thematic problems with the idea of an alchemist creating golems and so on, and plan to examine this in the future.

That said, if you really want to craft magic items you could try to:

• Obtain a spell-like ability with a caster level high enought to qualify for the feat (usually the racial spell like have a caster level equal to your caracter level, so those are handy) or
• Take the master craftsman feat at level 5, and then the craft wonderous item (useless, since your wizard buddy already has it, probably 4 level sooner) or craft magic arms and armors

If you are not bypassing the spell prereq for the item, you are forced to 'cast' it.

http://paizo.com/prd/magicItems/magicItemCreation.html

From the creating wonderous item section (similar text can be found in almost all other feat specific sections).

If spells are involved in the prerequisites for making the item, the creator must have prepared the spells to be cast (or must know the spells, in the case of a sorcerer or bard) but need not provide any material components or focuses the spells require. The act of working on the item triggers the prepared spells, making them unavailable for casting during each day of the item's creation. (That is, those spell slots are expended from the caster's currently prepared spells, just as if they had been cast.)

so in your case, each day you spent crafting the belt, you would need to use a copy of the scroll or have someone around who can cast it for you. Otherwise, you have to add +5 to the DC of the check.