What sort of shots do you want to take, prime focus through the scope or piggybacking?
I wouldn't recommend piggybacking off a nexstar mount because they're not the most stable of mounts, even with a heavier tripod. If you do, keep your lenses light and don't use large telephotos/zooms. You'll need an camera attachment with a 1/4-20 screw to attach your camera to the scope, either on the tube rings or a piggyback bracket.
Actually, your best bet would be to pick yourself up an iOptron sky tracker. Pop into Bintel and grab one from there
