My daughter slept so much better swaddled that we continued to swaddle her until she was about 7mo old! So I guess it depends on how well he sleeps. However, we did get wedges (like a previous poster mentioned) to put her down on her side sometimes (swaddled) and she slept great like that. But I also got her a memory foam "pillow" to keep her from having a flat head. I found the wedge system that came with a memory foam head area for that reason.
Here's one: http://www.mypreciouskid.com/baby-sleep-pillow.html
and another: http://www.mypreciouskid.com/baby-sleep-pillow.html and one more: http://www.onestepahead.com/jump.jsp?itemID=424758&it...
None of these is exactly what I bought (the foam was just a little half cirle about a half-inch thick for under the head) but I couldn't find it online anywhere. Maybe they don't make it anymore. But one of those might work for you.
My daughter's head never got a flat spot (thank goodness!), but I let her have lots of tummy time during the day and put in her a bumbo seat as early as I could, too. That allowed her to sit up, which she loved, and kept her head from resting on other surfaces during the day, like the bouncy seat and swing, as much.
Hope that helps. Good luck.
P.