I'm using Pro Tools' comping feature to use pieces of multiple takes. Can I make Pro Tools automatically create crossfades on the transition points between regions?
Yes, if you have your comped playlist, just drag selecting the whole thing (triple click with selector tool will highlight all the regions in the playlist - first to last) then hit command-F.
Now, regardless of if the points actually hit on the right places, seems to me that it's a bit dangerous to do so. I find that the safest place to create a crossfade would be in the middle of words, next to plosives or T's, etc. (not nasal or long open vowels). Doing crossfades between words of different takes usually becomes really apparent - either the singer stood away of the microphone on that particular take, or he/she is more tired (say, first take of the day and last as an extreme example). the time you'd spend re tweeking could be longer than creating the fades on the right place first time around?
I might be misunderstanding the question, but to automatically create fades, simply highlight any regions you want included, and hit command-f. The regions need to be touching obviously. Hope this helps.