If you have rooted your phone then I don't think you need an app to do this. Unfortunately, I am one of the people that cannot get their phone to root (I gotta go searching for the magic PNY 2GB SD card tomorrow!), to try it.
There is a properties file named incrediblec-keypad.kl in /system/usr/keylayout that you can modify to enable the DPAD to wake the phone. In the file, find the line for "key 232" (shown below) and un-comment it by removing the "#" char.
Code:
# key 61 CALL WAKE_DROPPED
key 232 DPAD_CENTER WAKE_DROPPED
# key 108 DPAD_DOWN WAKE_DROPPED
Save the file back to the original location (this part requires root access).
Again, I have not been able to try it myself yet. But this should do the trick.
Someone with root, give it a try.