I don't cross country ski at all, but it sounds like a good idea.
Some exercises I had conidered for training were walking lunges, jump rope, resistance exercises (maybe some things with those giant rubberbands?). Looking for some good core exercises too, my lower back often gets a little sore while running or biking, so I'm looking to strengthen that area. And strengthing the core usually improves general performace of most atheletic activities.
I'm entering graduate school this year so I don't really have much money, looking for cheap options.
I finished 8th in my age class, and was somewhere in the 60s for overall.