Bezier masks to isolate the 'objects' into layers. Gaussain Blur FX to thow things out of focus. Probably a heck of a lot easier in something like AE Pro with trackers and the Rotomask tool.
One quick trick you can try is to use lighting. From a grey scale mask derived from your lighting you can control the amount of GB. I saw a plugin that does just this for many, many dollars and yet you can do this for zip with Vegas or just about any NLE.
Having said that nothing you can do in post will match exactly what a lens does. Every lens type, make, model and serial number has it's own signature.
Bezier mask as pointed out is the way to go...but instead of using
gaussain blur (which really does not fully imitate that out of focus look).
Try getting "Radiance" from velvetmatter.com...included is a defocus
filter that hits that out-of-focus mark.