I have not confirmed this myself, as I don't have an Ascend -- I'm going by what I was told. It should not harm your phone, even if it fails, but you shouldn't fool with this unless you're willing to take responsibility for the consequences.
Make sure you have an SD card mounted
Turn on USB debugging
Turn on Unknown sources
Go to XDA and download the latest Gingerbreak.apk
It will restart your phone, and you should be rooted. Please report any success or failure, so I can update.