Just for posterity, here's what I ended up with. To recap, the problem is that my computer has a "feature" - an increasingly popular one - that power keeps going to the USB bus even when power is off, so you can charge your iDevices at all times. And with my BIOS, there seems to be no way of disabling it. This means my Pac-Drive-powered LED lights stay on even when the system is off, which is just silly - and my family nags me about leaving the cabinet on all the time and wasting power, even though it is in fact sleeping or shut down.
Shutting off the LED's at shutdown proved to be a delicate operation; it must be timed perfectly with other things going on at shutdown it seems. Plus, Windows' + Mala's startup time is enough to annoy a user who expects to push the power button and quickly start playing. So, I just gave up on having my cabinet's power button actually power down the system and lights. Given that power would still be flowing to my IPAC and Pac-Drive anyhow, there seemed to be little to gain from shutting down vs. sleeping. I put a piece of tape over the blinking light on the case when it sleeps, and kept my power button wired to the IPAC and mapped to sleep/wake. I also set up Windows to automatically sleep after an hour of idle time.
Now, the problem was getting my Pac-Drive lights to shut off when sleeping, and to start back up on waking. Initially I set up an AutoHotKey script to run "ledblinky.exe 2" upon sleep, and "ledblinky.exe 1" upon wake, but this ended up confusing the Mala plugin since this causes the ledblinky process to get a new process ID.
So, I set up a new screensaver animation with LED Blinky's animation editor that just does nothing, and assigned that to be LED Blinky's front end screensaver. When AutoHotKey gets notified that Windows is about to sleep, I tell ledblinky to start its screensaver - which turns off the LED's. When it wakes back up, I end the screensaver, putting ledblinky back to its previous state for Mala.
It is a sick hack, but so far it seems to work. Here's my AutoHotKey script if anyone else finds it useful (obviously substitute your own path to ledblinky - and set up that do-nothing screensaver animation first.) I compiled this script to an exe and put it in my Startup folder.
OnMessage(0x218, "func_WM_POWERBROADCAST")
Return
func_WM_POWERBROADCAST(wParam, lParam)
{
If (lParam = 0) {
; PBT_APMSUSPEND or PBT_APMSTANDBY? -> System will sleep
If (wParam = 4 OR wParam = 5) {
RunWait, c:\arcade\mala174\mala174\plugins\ledblinky\ledblinky.exe 5
}
; PBT_APMRESUMESUSPEND oder PBT_APMRESUMESTANDBY? -> System wakes up
If (wParam = 7 OR wParam = 8) {
RunWait, c:\arcade\mala174\mala174\plugins\ledblinky\ledblinky.exe 6
}
}
Return
}