XP can be granted for reading a book about a magic that doesn't require initiation and you can and should gain XP for it. This should hold true for all skills that are not purely physical, such as weapons skills.
From the grading guide:
Skills can gain XP by being learned from a book or verbal lessons, but not all. Skills that are purely physical, such as weaponry and hunting, may gain lores from books/lessons, but must be physically performed in order to gain XP.
Hope this helps! Keep in mind that finding said books is probably going to be very difficult and you should probably check in with the local ST about how to go about doing that.