lol that's awesome xD You know, I've wanted to do the same thing ever since my crazy Kimblee obsession began, but I'm afraid my job at Gamestop wouldn't appreciate visible tattoos, especially on the hands. Oh well.
Anyway, I've been wondering this same thing myself, and I just recently checked a bunch of pages from the manga. According to that, it seems like the words around his transmutation circles change in a way. Let me explain...
In Volume 15 you can see his transmutation circles pretty well, especially in one panel toward the end where he blows up a ton of Ishvalans with the Philosopher's Stone, and he starts getting all excited saying "WHAT A BEAUTIFUL SOUND" or something like that. xD He lifts his hand up to his face and you can kind of make out what looks like English characters. I swear, I can almost make out the word "madmen" which made me chuckle. But the rest is either a different language, or just plain nonsense. It looks like "o omidan batae osbin..." I have no idea. It's actually really difficult to read. xDD
In later volumes, like Volumes 16, 18, 19, and 22, you can clearly see the transmutation circles again, but the words don't look like a language at all. It actually just kind of looks like chicken scratches. I think this is most clear in Volume 18, page 56 (I'm not a creep... >A>) when Kimblee's explaining to Ed how he wants to carve a crest of blood in Briggs. He holds his hands up with his palms facing the viewer. The circles are pretty small, but you can smoosh your face close to the picture and see that the characters are pretty much nonsense.
Then, in Volume 23, you can make out the circles really well, ESPECIALLY in the panel where he says, "You won't be able to regain your original bodies NOR save anyone. You'd do well to beware of that outcome." (This is obviously when he's talking to Al about other possibilities other than equivalent exchange). This is probably the time when you can see his transmutation circle the best because it's very large and up close. Now if you look at it, it doesn't even look like English characters anymore. It looks like some other strange language with weird characters.
If you really want to go with the tattoo, I'd recommend studying those closely and figuring out what you want to do. On the bright side, at least the words are small, so even if you ended up having complete nonsense written around it, I doubt anyone would notice. xD Maybe taking scans of the manga to the tattoo place wouldn't be a bad idea? The guys at most tattoo places are really great artists, so I'm sure they'd know what to do with it.
Hope that helps! ;D