I think this lends itself more towards rituals than simple discipline, like Theban, Cruac, Gilded Cage, etc. Base it on something like Presence + Crafts and a willpower to activate to represent willing the tattoos into the appropriate shape to enact the ritual (also prevents double dipping with other rituals that use Int or Manipulation).
Then have rituals at the various dots, you get one for "free" when you advance the power, then buying more costs 2 x ritual level.
Using the example given by the other answers, you may see something like
• Shaping - kindred can shape his tattoos to hold some information, therefore he doesn't need to roll Int + Comp to remember it. The character can hold one piece of information at a time per dot in the power.
• Symbol of Defense: You bear the symbol of a powerful spirit that watches over you. The symbol may represent a religious icon, mentor spirit, personal totem, or the like. This grants +2 defense while active.
•• Library - all the kindred hears is stored as small bits of information inside his tattoos. Choose a mental skill. The character gets an equipment bonus to that skill equal to the number of dots in the power. This ritual can be purchased more than once, each time it represents a different mental skill. This equipment bonus can not be combined with another equipment bonus representing documentation or research materials (e.g. Chapter Library, etc)
•• Symbol of Luck: You wear the mark of Lady Luck, herself. Fortune smiles upon you. On your next check, roll twice and keep the better result. For example, on a Strength(3) + Brawl(4) check, roll 7 dice and count the successes. Then roll all 7 dice again and count the successes. Keep the set with greater successes. (For MET, pull two cards, keep the higher card.)
••• Camouflage - Kindred can shape his tats in a way, that they will act as a camouflage (+1 to stealth rolls for each dot), of course he needs to be naked to use this. This cannot be combined with another discipline, such as Obfuscate •••.
•••• Living Ink: You possess a life-size tattoo of an animal you choose. When this power is activated, the animal detaches itself from your body, and comes alive, acting under your command. When not activated, the animal returns to its tattoo form. The animal has the same stats as a normal animal of its kind. The animal must be chosen at the time this ritual is learned. The ritual may be purchased more than once, each one represents an additional animal the character can summon. The character can heal damage to the animal while it is in tattoo form by spending blood following the same rules as healing himself. If the animal is killed, this ritual must be repurchased. (compare to retainer, but can summon and dismiss at will, and has full control over the animal. It would be a 5 dot ritual, if animal retainers weren't already so limited)
Add ones that duplicate encyclopedic knowledge, eidetic memory, and so forth