In the FR accessory "Lords of Darkness", they have a way of handling Tatoo Magic. Basically, it's like Scribe Scroll with an alternate medium. Pretty bland, IMHO.
It requires the Tatoo Magic feat, which has the prerequisites of the Craft (calligraphy) or Craft (painting) skill and a caster level of 3+. The scribed tatoos take up magical items slots on a character, unless you pay double the normal cost. You can only scribe spells of 3rd level or lower. You must pay 1/25 the base price in XP and pay half for raw materials. The base price is spell level X caster level X 50 gp. It takes an hour to scribe a tatoo. The spell can be activated as a standard action which doesn't provoke an AoO, and the tatoo can be erased with an erase spell. Failing to erase a tatoo doesn't activate it.
I think Tatoo Magic ought to have a flavor all its own. The FR way is too much like Scribe Scroll.