Help setting Perl path

Hi,

I have Perl 5.8.8 installed by MacPorts and a CPAN install of 5.10.1.
Is there a simple way switch between them hopefully from the Terminal,
so I can use 5.10.1 when using get_iplayer and 5.8.8 for other programs.

In a previous post, it was suggested that I create an  
environment.plist. Using the following instructions:

mkdir $HOME/.MacOSX
cat > $HOME/.MacOSX/environment.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http:// 
www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
         <key>PATH</key>
         <string>/usr/local/bin:/usr/local/lib:/opt/local/bin:/opt/ 
local/sbin:/usr/bin:/bin:/sbin:/usr/sbin</string>
</dict>
</plist>
type CONTROL D

I assume this method is not temporary, but when I restarted my  
system, there was no change
to the version of Perl being used. And to be honest, I didn't really  
understand what I was
being told to do.

I know for many getting get_iplayer to work on there system has been  
relatively easy, but I just
can't get all the needed modules installed in my Perl 5.8.8.

Thanks,

Terrence