What type of TV do you have? That is the important question. My dad has a DLP projection and overscan is something he's been battling for a long time. Not much you can do if the TV is overscanning everything.
With the stock rom, you could try to change the resolution (420, 720, 1080, etc). Sometimes this can help with overscan. We found that at lower resolutions, the overscan wasn't as bad.
With his TV, we ended up using a S-Video Cable to get rid of the overscan, which isn't an option here (HDMI is digital so 1-1 output, where S-Video is analog).