It is already implemented.
If you'll see this complicated image:
http://www.mpegbox.com/DSATX/parameters.gif
If you'll notice, one of the parameters is "Enable5VSBOFF" and "EnableSleep"
If you clear these, it leaves the +5VSB on when ACC goes low and all timers expire. Unit will draw 20mA in this mode, plus whatever your PC draws in this mode..
Since you got one of the very first units, yours doesn't have this feature, and it isn't feild upgradable. If I loaded the lastest code, your scrambling eeprom and all these other features would be yours.
-Jeff