Very Computer

Hi,
   I would like to use one Linux box to host 2 hostnames. Specifically,
I wish to assign some users to one hostname, some to the other, so that
when they log in and communicate with the Net, it appears that they are
on one of two different machines.
   Progress so far:  using the R. Sander's alias net tools, I use
the alias "device" to set up a second IP #.  This works great (i am
using 1.2.13).  I've registered two domain names with the NIC, and
assigned one to one IP and the other to the other IP.  This works
fine too.  Now what I would like to do is assign some users to
one hostname, and some to the alternate hostname.  I guess what is
needed is an alias hostname command.  Alternately, I would like to
make it seem that some users are logging into the 1st IP#, some the alternate.
It would be nice to see "hostname -f" return the hostname corresponding
to the user's assigned hostname.  Any ideas?
andy mendelsohn