I went and had a look at the racing in Mackay just the other weekend, the track is at Kitchant dam, thats the dam stinky was talking about. You just head west about 40kms on Nebo road and follow the signs to Kitchant dam. You wont see any mountain bike signs anywhere. Just stop and ask someone if you have trouble. There is a real nice downhill track, there were some pics of it in the forum somewhere but i cant find them now (p.m. j5ive, he has the pics) also a nice 4x track and a xc track somewhere. Its worthwhile going out for a look.
Cheers...