Cards for Reanimator in Cube
The first thing you need to do is decide which colors you want to support the reanimator theme in. Black is the go to answer, but there are solid reanimation options in white as well. Enablers are going to be mostly blue or green. Once you know the color options, then envision what you want a good reanimator deck to look like in your cube. Do you want it to be a Legacy styled combo deck that can have Griselbrand on the field on turn 2, or do you want it to be a much more grindy Rec-Sur styled GB deck? You can also use cards like Debtor's Knell that give a good value BW deck an awesome late game by itself.

Balancing cards that can be used in both a dedicated reanimator strategy and other strategies is important. Cards that discard for a benefit, like Oona's Prowler and Lotleth Troll are perfect for this. Survival of the Fittest like cards are strategies to themselves, and just get better with a few reanimation cards. Draw/Discard cards such as Thirst for Knowledge fit great into reanimator decks as well. 

Once you know what you want your decks to look like, and you have a list of cards you want to include, then all that's left is to find slots in the cube and playtest. Force the strategy a few times, and see if you feel like you're getting enough support. Let others draft and see how often the strategy is taken, and how often it wins. If it's too powerful, cut back cards or add dedicated GY hate*. If its too weak, then add more support cards. If it's good but under-drafted by your group, then bean them with it a few times.

*A note about dedicated GY hate - I don't recommend adding these cards to begin with. They're dead cards more often than they're used. Instead try things like Scavenging Ooze (or if you're like me have Leyline of the Void and Helm of Awakening in your cube...)