Hi Pheelthemusic,
I'm also really interested in hearing a response to this question, I normally use the obvious multiband compression and limiting to taste, but convincing a band to spend some cash on pro mastering is a constant problem. At the start of every project where the budget is limited I explain that mastering is a different discipline and the reasons why it is worthwhile, but it very rarely is taken on board. As a result, I'm left needing to perform as a mastering engineer which is an area that I have no concrete expertese.
Tim.