I just got the D10 recently, but in playing with the display button and reading the manual, I can't figure out how to get it to turn off. I think it doesn't have that feature. Is that something that CHDK can help with.
I have this camera, and did the CHDK port. It operates as I described.
In shooting mode, go into the canon menu. At the bottom of the first page, there is "set <print icon> button". Set that to the camera icon with zZ over it.
Now in CHDK, if you hold the print button briefly, it will go to display off mode immediately. Pressing a button will wake it up. This is not quite like the "display off" mode on cameras with an OVF, the display will wake up every time you shoot.
In a chdk script, you can click('print') to simulate pressing the print button.
Note that if you use MF, the MF setting will be lost in display off mode (edit: the camera will revert to AF). If you use focus-at-infinity mode, it will not be lost.