Hi Jeff,
Short answer - (1) TX, (1 to 3) EX/RX
Computer---USB cable--- Dongle ---CAT5---TX(transmitter)
LE with wireless receiver
LE with wireless receiver
LE with wireless receiver
or
Computer---USB cable--- Dongle ---CAT5---TX(transmitter)
LE with wireless receiver --- cat5 to other two LE without receiver
You can mixed and match wireless with wired or just use all wireless if possible/needed.
Rick R.