I only know how to set Slic3r up for this; there may be instructions for other slicing software - you'll have to google it or ask for help here. It looks like you're using a version of Slic3r integrated with ReplicatorG. I would recommend downloading the latest version from slic3r.org and using it separately to generate your gcode, which you can then copy across to your SD card.

In Slic3r:

1. Go to Printer Settings and under the General tab, increase the number of extruders from 1 to 2. You should already have "Extruder 1" in the list on the left of the window; increasing the number of extruders will cause a second extruder to appear.
2. Click on Extruder 2 and set up for your printer. I'll assume this extruder will be the one PVA is loaded on. Set your nozzle diameter, extruder offset and other settings for your printer (hopefully you know what these are). The retraction length should be 0 for PVA. Save the printer settings.
3. Go to Filament Settings and create a new set for your PVA filament. I understand printing temperature should be about 190C, but look to the manufacturer for the recommended temp.
4. Go to Print Settings and click on Multiple Extruders in the list on the left. Select the second extruder for support material.
5. Go to the Plater tab and you should now see to combo boxes under Filament. Select your PVA filament settings for the second combo box.

You should now be able to load an STL file in Slic3r and generate the gcode for your ptiner. This is a really, really, really abbreviated set of instructions, but it should get you started. It's difficult to get more detailed without more info on your setup. Things to watch out for include nozzle offset, making sure your existing settings carry over from an earlier version of slic3r, making sure the correct nozzles are selected for each filament.

Hope this helps.