Are the three outputs the same duty and freq or do they need to vary independently duty / freq or both?

I use 10-90% duty sspwm at 2khz on an 8mhz pic put only on one output it works very well.

If you only need one output active at any one time you could just direct the sspwm to the reqd pin at the reqd time.

If you need two or more working then you might be stuck.