Regarding Dokucraft there's some partial support.
IC2: http://forum.industrial-craft.net/index.php?page=Thread&threadID=2310
BC/RP: http://www.minecraftforum.net/topic/692070-dokucraft-industrialcraft2-bc-addon-32x32/
Can't really answer to the quality of said textures, but whatevs.
In addition, there is some middling-quality texture addons for Isabella for all the mods in tekkit, found here:
http://www.minecraftforum.net/topic/882510-scotts-unofficial-isabella-mod-support-center/