H2OENG,
"I'm wondering how you could get the water JUST from the middle of the cup without using a solenoid valve, etc."
How about this:
The skimmer neck has an inner & outer cylinder. The inner is the riser tube with wetneck ports, and the outer cylinder forces water to be pulled from the middle of the collection cup to go back to the tank & feed the wetneck.
Heres a pic. The dashed horiz line is the water level. Once the level in the collection cup reaches that, it will start dumping back into the skimmer body via the wetneck ports. If you run it wet, will you get a more effective skimmate????
Stu