Mastering is an artform and is not something that should be left up to somebody that doesn't understand the process.
There are a couple programs out there that are for mastering.....but I think they are a joke. If anything....you would need some good plug-ins. I use the Waves L2 for limiting and Q10 for EQ when I do my "ghetto mastering" in Sound Forge.....but I take it to the professional mastering facility when I'm mastering a CD for presing.