I've converted the GF flour recipe in the Thermomix GF Recipe Book. I've used it successfully for two cakes so far, but haven't tried anything else.
Megan's Gluten Free Flour
250g rice flour, made with 50/50 brown and basmati rice
190g Maize Flour (pure cornflour or cornstarch)
125g Tapioca Flour or Arrowroot (interchangeable in Australia)
125g Sorghum Flour
60g Potato Flour
1 1/2 tsp Xanthan Gum
Grin rice on speed 9 for 1 minute. Allow to rest for a few minutes and grind again for a minute. Repeat until rice is a nice fine flour. If bowl start to heat up, remove from base and allow to cool.
Add remaining flours and gum and blend 20 seconds on speed 6.