installation on postgresql on different port

Hi,
  Anyone pls. help me. I have a postgres installation package for Mac  
OS X.
  After installation, Can i use my own user for configuring postgres,  
instead of creating a postgres user.
Also how can I run it on different port, instead of the default port  
(5432).
And lastly how can I uninstall postgres. I am using Mac OS X Tiger.

Thank you

Regards
  Vijai