I'm just going to say this: clematis are not houseplants. The conditions we can offer from inside our homes are just not to their liking. And this is the same for any plant native to temperate climate locations - they do not thrive indoors. You may get one to grow for a while, but it is unlikely to bloom well (if at all) and will be prone to insect and disease issues.

Agree wholeheartedly with the one caveat that if you have a greenhouse or conservatory you can probably get away with it, but a window in a house is not going to provide the type of exposure that will allow for the long term health of a clematis.

could you suggest any type of climbing or vine-like plant that would do well? Only caveat is no root stems as their form of climbing as I'd rather not have to deal with them getting into the walls >_>

How about a varigated ivy on a trellis or a system of strings going around you window. Have also seen philodendron growing around windows. Or that varigated vine that looks a bit like philodendron but with larger leaves. Have one downstairs, just can't remember the name.