Due to public demand (are you lot mental?!), I've put together a 50 Pull-Up Challenge for you. However, as it's an Excel file, it won't attach, so if you want it, PM me your e-mail addresses and I'll fire it over.
For form, see this link:
http://www.ehow.com/video_3192_pull-.html
If you're in OHW's position on this one, try doing weeks 1-2 using negative pull-ups first (see video link below - keep to the overhand grip as demonstrated in the first video, this just demonstrates the principle of a -ve pull up).
http://www.youtube.com/watch?v=Opr72q6NKTc
Once done, do the initial test for a proper one - you should by now be able to knock out a couple at least.