Is it possible to combine OpenCoop and Sikkmod?

What the title says -- I'd really like to play OpenCoop with the graphical enhancements of Sikkmod. I'd ask over on doom3world forums, but it seems to be down.

Anyone know how to go about this?

Try one of the solutions mentioned here: http://www.doomworld.com/vb/doom-3-general/45183-can-i-run-multiple-mods-atT-once/ Either copy both mod's contents into a new directory and launch it as a new mod, or (better) launch Doom 3 with the command line parameters from kristus's post.