open dfx3.0 in skineditor, delete the flash movie box (where the logo's go), replace with a label add "GPSSPD" as the code. tweak font to your liking
Edit: if you want me to do this for you, send me a pm. I just need to figure out how to make it so the font changes color with the rest.
Edit: or instead of deleting the flash movie, you could resize it and make it smaller, so you would have both gauge and digi.
here's some SS, don't pay attention to the ugly colors, it's so I can tell the difference between my good skin & test skin, my taste isn't that bad
PICTURES REMOVED DUE TO MY FEELINGS GETTING HURT.
or they are no longer needed and taking up space