Minecraft – How to /setblock a specific type of redstone (Debug mode)

There are a number of methods for extending a redstone signal:

Repeaters

Just plonk down repeaters. Each one gives you another 15 blocks, however, there is a 1-tick delay in the signal for each repeater you use, which can slow down large circuits.

Instant Wire

This allows for instantaneous redstone transmission over long distances. There's a wiki page for it! It's a little complex, so here's video:

Should the video go down, a search for Instant Wire will turn up many more.

Mods

MineFactory Reloaded has redstone wiring that can extend for supposedly unlimited distance, preserving signal strength, using a network system.

Here's the structure of the /setblock command:

/setblock x y z block data method [dataTag]

xyz are the coordinates of the block
block is the TileID of the block (includes id:0 now!)
data is the block data (i.e. 5:1 spruce wood)
method is one of three things: keep, replace, or delete

• keep spawns the block at the coordinates.
• replace replaces the block at the coordinates with the block ID.
• delete removes the block at the coordinates and then spawns the new one in

dataTag (optional) is tile entity data.

From Minecraft wiki