Should just have to get an IT slug drilled.  But the deal with it is that the slugs themselves are drilled at 0 pitch, and the hole in the ball is the one that is pitched, just like if you would use a regular slug.  You can drill a bit of pitch into the slug itself, but any more than 3/16, depending on your thumbsize is gonna cause problems.  You may have to get the whole thing redrilled.  So step 1 is to see what the pitch is for the thumbhole in the actual ball.  If it's within 3/16ths any direction, you should be in business.  The next step is to see what size the hole is.  There are two sizes of IT slugs, the standard 1 1/4 and 1 3/8.  If it's 1 3/8 it would probably help you out more, seeing as you would have more room inside a bigger slug to adjust pitch if needed.  Those two things are all you should really need to check.  Now, your driller will have to make a note, because if you like the IT system and transfer your other balls over, and your pitch isn't the same in your other stuff as the ball you just picked up, he will have to adjust the pitch to match that ball when drilling your other stuff.  Hope that helps.