you got the double wammy going there man! An easily melted substance (wax) coupled with and highly abrasive substance (can you say heat).
when machining plastics (wax fits this catagory IMO) you generaly use slow sfm to reduce melting and higher feeds (because you can) 400sfm for wax actually is an ok 450sfm is what i have run before (although no abrasive) build up at the IPM is probably a given. Because I dont know if a 1/2" 2 flute End mill is going to give enough chip clearance at ruffly .024ipt (that a large chip that is probably going to get jammed in a tiny flute and the fact that the abrasive is generating heat and probably no coolant, do to the material (you didn't say so I assumed)) If this material didn' melt so easily i would say try a faster sfm (to reduce chip build up, but since this isn't the case maybe a Cool air nosle or just straight compressed air as your coolant might be to trick (for the buildup at least).
without knowing more info cant realy say much but it looks like the compressed air idea is the way to start, then if that is looking like the right direction maybe a cool air nosle for prolonged cutting. Unless of course you can use a liquid coolant.
sorry I couldn't be of more help.
thanks
Michael T.
"If you don't stand for something, chances are, you'll fall for anything!"