Yes, you can. No, you don't need the install disc. just backup the bootcamp partition with Winclone. then erase and resize the old partition. then restore the image to the resized partition. you'll have your additional space without any problems.
to do this, though, Winclone has to be configured in a very specific way.
Winclone --> Preferences:
uncheck "Remove pagefile.sys from..."
uncheck "Compressed"
uncheck "Use ASR"
^ set it like this before backing up. then do your back up, erase + resize, and restore.