I can confirm Asus P5B-VM DOES support wake on usb via mce remote.
It's not just a matter of jumpers and bios or pairing PSU/MB (even if this effectively ARE serious issues)
The only thing I had to dig into is the remote receiver configuration; I did that via MCECustomizer ("Enable Universal Remote"..or similar), and this is the behaviour:
Apparently the remote receiver is NOT powered, the little led NEVER flashes with ANY button; BUT "Powertoggle" or "On" resume the pc from S3.
With an old mb I had a totally different behaviour: EVERY button made the little led flash, and "Powertoggle" or "On" did resume from S3.
So I had some trouble, because thought that the receiver was not powered; but the point was instead a software configuration problem.
[Harmony Remote 688/Mce Receiver, P5B-VM with Antec Fusion Case]
Hope this can help
Bye