Apple Logic Pro /LogicExpress Discussion

Hi,
Back once again with another question. I'm successfully using a MOTU microlite 5-in/5-
out USB MIDI interface to provide external control of some rackmpunt synths, but all 5 in/
out ports are used. I'd like to add two more external units to bring into Logic and have an 
old Opcode Studio 4 serial MIDI interface. Is there any way I could incorporate this into my 
setup for extra MIDI ports? I know Logic should't see it if I just daisy chain it via MIDI to 
the microlite, especially since the Studio 4 is a serial device. 

Thought I'd check befoe shelling out the cash for a second microlite.

Thanks,
Doug