Cellarmix is not of much use to HBers, the nitrogen is there only to push the beer from the cellar or from quite a distance to the taps. If straight C02 where used the pressure would over carbonate the beer.
You will waste lots of gas with cellarmix, in fact all the nitrogen.
cambrew, you said in another thread that you went with Cellamix on advice, I assume from a person, at BOC?
If so, mate, take it back and say this is not the right thing for me and I need C02... Which hopefully is what you originally walked there and asked for?
Anyway, don't stress it man, learning is learning and I am sure if you play the heavier hand you may end up in front or at least even over the confusion....