@ Mori - Unfortunatly you cant just loose weight in a certain area of your body !
You'll need to just cut out alot of carbs, stop eating bread, unless its for breakfast, dont eat after around 7pm, (later if your a night owl, just give it 3hours or so before bed) If you eat Pasta and Rice, make sure its brown. Oh yea, and small portions, but eat 5-6times a day, this gives your body the most oppertune circumstances to burn your bodyfat, eating 2 massive meal a day is too much in a short period, your body doesnt need it all, so whats left gets 'stored'.
From the pic you look like your a big guy, and not one of the skinny toned guys. This unfortunatly makes Abs for you even harder, naturally skinny guys only need to tone their abs with a few situps, leg raises and V-sits. For bigger guys you actually need to build your Abs up. This means weighted crunches.
Alot of gyms (uk) have a crunch machine, which is great, stack up the weight and go, but you said jail-house-style. My best recommendation is to do crunches at home, but just hold a weight on your chest, doesnt have to be much, start with 5kg and work up
*Edit*
You mentioned p90x, a quick google search said this is a 90day home training kit. My honest recommendation here is, these are all bullcrap. If your not motivated without it, you wont be motivated with it. You said a friend has it, and it worked, ask to check out the DVD's, they'll most likely be repeating things you already know, just in super-dummy-language.
*edit2*
Here are download links to the DVD sets. These arnt hosted by me, but let me know if the links go dead and i'll see if i can find new ones.
Code:
http://www.BigAndFree.com/12127051
http://www.BigAndFree.com/12127378
http://www.BigAndFree.com/12127379
http://www.BigAndFree.com/12127380
http://www.BigAndFree.com/12127381
http://www.BigAndFree.com/12127382
http://www.BigAndFree.com/12127383
http://www.BigAndFree.com/12127384
http://www.BigAndFree.com/12127385
http://www.BigAndFree.com/12127386
http://www.BigAndFree.com/12127387