how to upgrade from 3.04 to 3.1

Tue Jun 4 10:12:00 GMT 2002

hi,
i have been using 3.0.4 and want to upgrade
to 3.1.
the documentation says:
"We strongly recommend to install into a target directory
 where there is no previous version of GCC present."
thats ok, but i'ld like to have the compiler
in its usual place (for me its /usr)
where already the 3.0.4 sits.
what can i do?
i'ld like to get rid of the old one (3.0.4)
but i need it to bootstrap the new 3.1.
 cheers
  christian