3/4 length winter baselayers

You can look into bicycling non-padded tights & knickers. Lots of options.

All you need is scissors and a lighter. Works great with ski boots.

Why not take a look at women's baselayers? Those will be shorter than the men's versions.

Both ibex and icebreaker have men's cropped bottoms. I think minus33 might make a similar version as well. If you have a ski shop near you they'll probably have a decent selection.

There's also arcteryx phase SV boot cut. Cap4 feels a little warmer to me…but phase SV is still pretty awesome stuff.

Some retailers have filter options for length, e.g. Backcountry.com: http://www.backcountry.com/mens-long-underwear-bottoms?p=attr_pantlength%3A3%5C%2F4%5C-Length&nf=1

I cut a pair of Cap 4's to just below knee length; I also have a pair of MH Mighty Power 3/4 length tights-usually use those for running, but they would work as a base layer in cold conditions you don't mention pants, but OR makes a 3/4 Ferrosi pant with a Schoeller-like material that are very nice