I wrote VBA code (in MS Word) to create an XML queue file of all tracks from my iTunes "Music" folder that I ripped after a given date only. The date is selectable. This is to avoid MC having to go through the entire Music folder every time, adding it recursively and telling MC to skip duplicates.
MC is missing some advanced selection functions and filters, but you can use the XML queue to chose which specific files to convert. The trick is creating the XML file containing only the files you need!
If anyone wants a copy of the code post here and I'll figure out a way to upload it.