I'm running cooker also, and so far, with kdebase-3.3.2-18/kdelibs-common-3.3.2-25, the menu's side bar still haven't been updated.
Here's what I did (BTW, I an using the korrilla icon theme so you might have to adapt to your theme):
cd to /usr/share/apps/kicker/pics and copy the kside_download.png and kside_tile.png to /home/user/.kde/share/apps/kicker/pics (If that directory isn't there, make it).
Then, open the copied kside_download.png file with The GIMP and select the "3" and copy to a new image. You can then copy this new image to the original, making it "3.3.2" or whatever you want it to be. Be creative and save the file. When you log out and log back in, you should see your modified menu side bar.