The basic idea behind service discovery is quite simple: Tyk can works with any service discovery mechanism if it provides JSON output. In Tyk configuration file you just provide JSON paths to needed values. Zookeper, like most of similar systems basically is key/value storage. And if you can store JSON there, Tyk will support it. Just configure proper JSON paths according to documentation.
If you already have example JSON record which you use for service discovery, you can put it here, and we try to help with Tyk configuration.
Hope it make sense!
Leonid, Tyk Team