Another postgres user/group name possibble?

Hi,

I've got a bit of a complicated problem here with a postgres user
already existing on the network I'm on (and having /dev/null as its
home).  Is there a way I can something other than ``postgres'' as a name
for the Postgres superuser and group name?  I don't know why anybody
would create a postgres user on our network, but I would just rather not
deal with it.

Thanks,
Richard.