If you have a Windows PC, then MS Reader may be your best option. Explode (extract) this with "ConvertLIT GUI" and point Windows MobiPocket Reader or Creator onto the .opf file to convert to MOBI. If you use MobiPocket Reader the MOBI will end up in your default ebook directory (My Documents\My eBooks).
The best place to start to look for copies of the mobidedrm python script is in the responses to
DarkReverser's Weblog. Since 0.05 just came out, start with the most recent responses. The Dark Reverser originally posted the python script (source code) to pastebin.com, it gets deleted from there periodically but if you find it there the download is .txt which needs to be renamed .py.
You have obviously format shifted other DRMed ebooks, but don't forget that this isn't necessarily legal (even for personal use) depending on where you live.