have you tried just swaddling the upper half of his body, but not his legs? He wouldn't be able to kick his way out, and would probably feel pretty secure. I really don't understand why, but my youngest didn't like co-sleeping when she was uber tiny, unless it was just laying on my chest, which I didn't feel comfortable doing at night, so I ended up buying a rock and play, and I feel like it was a great investment. I'll never buy a bassinet again! There are no batteries or music or anything, you can rock it by hand, or use your foot even.
This is the one I have, but if you feel it's too girly, they make one with a monkey instead of a bunny now. http://www.amazon.com/Fisher-Little-Snugabunny-Newborn-Sleeper/dp/B005IWM73S/ref=sr_1_2?ie=UTF8&qid=1353398966&sr=8-2&keywords=snugabunny
I used it from 7 weeks-5.5/6 months