[X-Unix] question on darwinports

[sham khalil]

hi,

I wanted to compile a printer driver, but it required autoconf 2.59 and 
newer gm4
my panther have autoconf 2.54 and older gm4.
I installed both autoconf 2.59 and newer gm4 from darwinports.
darwinports defaults install location is /opt/local
now i have both older and newer version of autoconf and gm4 installed 
on panther.
when compiling the printer driver with make, by default it used old 
autoconf and gm4
i solved this issue by temporarily removing old autoconf and gm4 binary.

how do i make new ports replace the old ports during install using 
darwinports?
how do i remove old ports safely?

tq
  sham khalil