I'm sure you already know but V23 will machine STL files directly. The results - vary. STL's are notorious for being very large files and the larger they are (the number of triangles, not the overall size), the more difficult it is for BobCAD to manage the data.
If you have a sample STL file you would like to run a test on, post it up and I'll generate some code for it.
EDIT: There was a good post on this subject at the BCC support site. A fellow was attempting to do this file http://www.cnczone.com/forums/showth...ighlight=tiger (tiger) and the odds of success were not good. The BobART add on had better luck but it was still tricky.