I believe the support for USB webcams has been added to the latest Kernel img
I managed to get a Logitech C250 webcam working with raspbian with the V4L driver
I used the following apt-get commands from a terminal
sudo apt-get update and apt-get upgrade
Also ensured that the cam was getting enough power from my hub and not back feeding power (cut the red wire inside USB lead) to raspberry. I have also seen blog posts showing a method about pulling down the img from the raspberry pi git hub and replacing the one on the SD card.
Mine worked using the apt-get commands and a modified USB lead to which the pi was connected.