Yes, you can get promoted while in CMF 18. It is a faster promotion rate. And if you're an officer, it is possible to become a General.
Monty and Jeeper - it is incorrect to say that enlisted SF Soldiers use the same promotion rules as other enlisted Soldiers. SF Soldiers may be promoted without waiver to E-4 as soon as 12 months without regard to normal TIS and TIG rules. SF Soldiers are also promoted to E-5 immediately upon completion of the Q Course without having to be recommended for the board. Also, those who are already boarded are immediately promoted to E-6 upon completion of the Q Course. Otherwise, they can be boarded and promoted to E-6 without regard to TIS and TIG rules as soon as they get to Group. There are several other advantages for those starting out in MOS 18X. The Q Course is also the equivelant of WLC and BNCOC for NCOES requirements. Also, when you consider that each line company (minus HSC) is run by a SGM instead of 1SG, then you can see it is not that difficult to stay in Group. There are handful of other positions in Group filled by SGMs. And - the USASOC Commander is a 3-star.
AR 600-8-19 Enlisted Promotions and Reductions