In FL Studio (version 4.2 & above):
Go to Options -> MIDI Settings, select '1:EDIROL PCR 1' in the 'Remote control input' section. Then select the 'Edirol PCR-30/50' in the controller type selector.

Now dump the included MIDI file into the PCR, using the PCR Editor application provided by Edirol.
You can optionally offset the key velocity by 64 (see PCR manual), which is more convenient in FL Studio.

Mapping:
Stop/Start/Continue message work as expected.
Rotary knob 1 is a transport jog, to slow down/speed up the song.
Knobs 2..8 are freely assignable.
Sliders 1..8 are freely assignable.
Button 1 & 2 are backward/forward buttons.
Button 3 switches the recording mode on/off (lit=on).
Button 4 switches the step editing mode on/off.
Button 5 is a freely assignable button in latch mode (handy for vocoder or granulizer hold button, etc.).
Button 6 is a freely assignable button in toggle mode (handy for mute switches, etc.).