I make beers with mostly unmalted millet and buckwheat, but the malty flavors come from a few pounds of malted rice. If you cant get any GF Malt youmight add 1 lb of D-45 candi syrup instead.
If you can get a Thermally stable alpha amylase (like "Termamyl").
Grind grains fine.
Add 14 lbs of grain to 4 gallons of water, add 2 Tbsp Termamyl. Heat to 180 F with constant stiring. Rest at 180 F for 2 hours.
If you canot get thermally stable alpha amylase...Cook your ground grains (as you would cook rice), instead of the 2 hour 180 F mash.
Then adjust the mash temp to 65 C and add your enzyme blend, hold at 65 for 1 hour.
Add ice to reduce the temperature of the mash to 65 C, add your enzyme blend and
rest at 65 C for 1 hour.
Sparge, boil as usual, and add 1 lb of D45 candi syrup at flame out (assuming you did not use any malted specialty grain).
I apologise for mix of english and metric units...are you in Australia(the link you posted was for an Ausie product)? If so you will understand the mixed units.
Feel free to PM me if you want more detail.