Yes I've done this. You have two options:

1. Using the old chaining 2x bolts: knock the knurled bolt out of the old chaining (may need to whack it with a hammer) and insert it in the new ring. You will need to get some chainring bolt spacers (as the 8mm 2x ones are too long for 1 chainring); or
2. Get new 6mm 1x bolts. Use one of these for hidden bolt too (no knurled bolt).

In both cases, if your crank is the Sram Red without a removable spider, you probably wont be able to tighten the hidden bolt to spec (even the knurled bolt in the new chainring may slip). I've found you can tighten it "enough", and as long as the other 4 bolts are tightened to spec, you shouldn't have any issue. I've never had.

If you have a removable spider, remove it to be able to tighten the hidden bolt to spec.