I really want Oil Lakes in our game, but really don't want them in the Twilight Forest dimension. Would be great to have a blacklist of dimension ids to not spawn the lakes in.

Yeah, good idea. We can add that.

This is added in dev now, or you can test it with build 145+ from http://jenkins.k-4u.nl/job/PneumaticCraft-Repressurized/

See I:oilWorldGenBlacklist in pneumaticcraft.cfg, e.g.:

# Oil worldgen blacklist: add dimension IDs to this list if you don't want oil worldgen to happen there.
I:oilWorldGenBlacklist <
  1
  -1
  7
>

Added 7 there, which is the default dimension ID for Twilight Forest.

Seems to work fine. Well done, and in record time too :)