Hmm. Could you mux it like this?
Code:
var counter byte
counter = 0
mainloop:
select ( counter // 5 )
case 0: outh = 255
case 1: outh = pwm1
case 2: outh = pwm2
case 3: outh = pwm3
case 4: outh = pwm4
endselect
counter = counter + 1
goto mainloop
Considering that the RC runs at ~40Hz, if you output four PWM values, along with a sync value (might be unnecessary), you'd get ~8 output values per second.
I have never written a dashboard program, so I don't know the intricacies of doing this kind of thing. Sorry. Just a random thought.