Yep. The installation manual for the pitot tube has several links to builders' sites with details on this. Biggest caution is *don't drill into the pitot and AOA tubes inside the pitot tube itself*.
Yes, 6/32 is the go.
I drilled the mast first, then inserted the pitot tube in and marked it.
Then drill the pitot tube in a drill press.
It's a bit fiddly to get the hole angles correct, but as mentioned above, there is lots of good info around.
And after you've removed and reinstalled the pitot from the mast a few times, you will ultimately strip out one or more of those 6-32 screws - and you'll end up enlarging them to #8 screws. 2 out of 4 on my airplane (10 years and just over 2000 flight hours) now carry #8 screws.
But yes, 6-32 for the initial holes, and that leaves you enough material to enlarge later when they strip out.
A good reason to mount it in a location such that you don't *need* to remove it unless it's failed (or, in my case many years ago, subject to a recall/replacement). That was the only time I've ever removed it, in 1000+ hours.