OEM v2.x is in designed for 3 tier architecture.

Console -- OMS -- Respository

This is done so in order to use thin clients in Console.

To install OMS get your 8i CD and install management structure part, after this instllation you will see a new service called Oracle Management Server in your services, just start it and then you can connect to that server from your console in other machine or the same machine where OMS resides.