hopefully i can help some of you out a bit on both of the topics here. for the chin ups without a bar, 10 years ago i invented just a device called the Jungle Gym XT, it simply goes over the top of any door and hangs off of it and allow you to do assisted or un-assisted chin ups.
Secondly the how to eat as a vegan for strength and conditioning...this is all we do at the monkey bar gym...we're the ONLY gyms in the world who promote a plant based diet and we have tons of menus and articles on how to eat plant based for fitness and athletic performance. i'm happy to help people in both of these points if i can help out at all:)
sincerely, jon hinds
www.monkeybargym.com

Tony Horton's new book, Bring It, discusses diet. Around page 220 or so, he addresses what should be removed from your diet. He addresses the subjects sugar, gluten, animal products, etc. and suggests alternatives. You might be able to get some ideas from this source. I have done P90X several times and have not found a Vegan diet to be an issue. You might also try the Brendan Brazier Thrive Books.