Hi,
Yes this is not possible in weblogic 6.0. It is possible in weblogic 7.0 however
In weblogic 6.0 before you try to start a managed server you need to undertake some configuration like (perhaps) setting up multiple IP addresses for the same machine. I am not sure of the process however but read something like it in the documentation.
If you are experimenting with clustering then i think
you should download weblogic 7.0 which will make life easy for you.