I don't see why not as I'm sure people drill CF helmets. BUT I'm not the manufacturer of your helmet and it's probably best to ask them 1st.

 

I tried putting the HANS posts in with the helmet on my head and it didn't go so well.

 

Got the helmet drilled, was pretty easy. I drilled a smaller pilot hole to get the 1/4" bit started. There was a bit of fiberglass left in the hole which made it a bit of a pain to thread the post into the anchor base but otherwise not too bad.

A note for anyone installing anchors. Most instructions/videos say to aim the pointy part of the anchor backwards. I found it a lot easier to anchor them backwards but downwards at an angle. When you wear the helmet your head is tilted at an angle so angling the post downwards make it easier to click the tethers in and out.

 

Ideally you want the pointy end of the anchor pointing straight back when the helmet is on your head. So when the helmet is sitting on the table, the pointy end will be angled slightly downward. Sounds like you got it right.

 

Right, I originally had the pointy end parallel with the table but I found that when I was wearing the helmet what felt like pushing the anchor straight back actually wasn't. Since your head is tilted at an angle you actually have to aim the point part a bit downwards in addition to pointing backwards.