Is there some way to use the default oblivion lich look in a robe or something? I've seen mods that allow you to wear zombie "Clothes" and look like one

How would someone go about creating that and are there any mods that offer such a thing?

Well, I think that for those you might have to create a new model for that in an armor, or there is a possible way to move the human skeleton into the lich. T
hough a way without needing to do anything to the original model (Mostly) and not needing to do any modeling is to create a playable lich. Using a tutorial found http://www.tesnexus.com/downloads/file.php?id=31821 you can make a lich skeleton able to be put onto the player using scripting to make them appear as a lich when wearing the armor.
Just throwing out that idea, and good luck on your project.

Thanks a lot for the help, I appreciate it very much. I'm going to get familiar with nifscope and see if I can't do something with this