I was a fairly competitive collegiate skier, and less successful runner in the 80s. I gave up roller skiing as I didn't think it provided much positive training for either skiing or running. The dynamics of roller skiing are not the same as regular skiing-it's slower and heavier. I didn't feel it provided the "spring" in my legs like regular skiing did, and it did nothing for my running. I thought snow skiing, either skate or classic was good cross-training for running-though I think Classic is better for running. Running was good aerobic cross training for skiing. Running lacks the upper body component needed for skiing, but I found swimming, an incline board, or this little device called an exergenie was better for skiing strength than was roller skiing. The exergenie probably doesn't do much for skate upper body (you can tell my career was at the dawn of skate skiing)
Perhaps the roller skiis are better now, but in my day, I thought they were a waste of time, and a good way to lose a couple days to road rash.. Have you thought of biking, elliptical training, or swimming as a cross training technique? An elliptical workout feels more like skiing than just about anything I've done. Since this is track, focus on track. If you want to roller ski, do it in July.