Without you further specifying what you're trying to do, the short answer is "ripping to FLAC is just like ripping to MP3 in MC". The files will be larger, but that's about it.
If you're concerned about preserving metadata of previously ripped files, then you could have some work ahead of you. (eg you have a previous rip of Song_A.mp3 and now want to make a new rip to Song_A.flac, while preserving the metadata from Song_A.mp3...)
I think a forum search for "rerip" will give you a start at least, if that is what you're going after.