The only realistic option to get to Morocco from Portimão is via Seville and Algeciras by bus/ferry.
See this page on my blog for more background info: http://goo.gl/zJdSN
As regards the Morocco side of the trip, I suggest you post in the Morocco forums.
One other new alternative, albeit rather convoluted, might be to fly from Faro Airport to Porto Airport and then from Porto Airport to Marrakesh. Both services operated by Ryanair.com. The flights do seem to tie in going, On the way back you might need to spend a night in Porto.
You could also train or bus from Portimão to Porto.
See Cubsur's excellent site at:
http://www.algarve-bus.info
