Printing with multiple heads?

How do I configure repetrel to use two heads (MK1) on the same print?

1. Having one head printing the support (generated by slic3r) and the other the actual print.
Just to set the extruder number under:
Slic3r, Printer Settings, Multiple Extruders, Support material extruder + Support material interface extruder to the extruder number. ex. 2 (for head 2).
right?

2. Have each head assigned its own .stl file and then print them both .stl at the same time.
Dont know how to do this, do I need to generate gcode and manual merge them or is there a better way?

Have also notice that even though I have added two extruder in Slic3r Printer Settings, the material is not selectable in Repetrel.
I was expecting the Printer Settings in Repetrel Slicer tab, Filament Settings to update so I can select material for the second head?
(And I dont know if I need to set the offset or if this is handled by the firmware?)

Maybe there is a guide how to get started on this?

Cheers
-Carlberg

AC,

As I mentioned, using two heads to each print different portions (be it support or a second .stl) currently requires a LOT of hand coding. This is automated in the next version, which is due out this month.