Last I heard IQueue was “discontimued”, i.e. no longer supported/updated…don’t think it runs in OSX.
Theres a few other options. Alwans CMYK Optimizer is particularly interesting and I’ve heard good things about GMG Color Server, the latter being a 4-D propreitary solution (non-ICC). I plan on getting a demo soon. There are vaious other means to do this also…Dalim Twist for example, and some PDF specific converters.