short answer: plug the usb wifi dongles into your computer, they should all show up in network manager (if they are supported) as wlan0, wlan1, wlan2 etc...and yes, you can connect them all to your router, however, you won't notice any difference in speed etc, because each app on your pc can only use one internet connection
and not several at the same time... hmmmm, maybe not such a short answer after all :)
