You want to know what to use to emulate bullets right? I don't think there is anything in 1.4.3 that can match what bullets will be able to do, but you could just make the time step as small as possible and try not to use too many shapes.
I am using Flash too, and in my current project I have hacked box2d to have sensors successfully. I am making my projectiles as sensors and they are flying pretty fast, so I made them a little bigger than their graphics will be to close the gaps a little.
Getting sensors working in Flash is actually not too much trouble, you can find my post about it by searching for sensors on this forum. If you have problems let me know.
I would suggest also just doing a smaller project that doesn't require bullets until 2.0 comes out. It doesn't seem like it will be long judging by the pace of the updates to the SVN.
Other than that, I think CCD/bullets are actually finished in the SVN, we are just waiting on a few other small features for 2.0, so if you are familiar with C++ you could do your own port of the CCD code