How to create 2 versions of a port

[Fbsd8]

I maintain a port that accesses the release distribution files. Now with 
9.0 having a different path /i386/i386 and the files being compressed 
first with tar and then again with xz I need to change the port to 
access the new layout and file format.

I would like to leave the current version in the ports as is which works 
fine with the 8.x world and add a second version that only works with 
9.0 and newer.

Question is how do i change the port description of the current port to 
say it supports 8.x with out re-adding the complete port again?

I know I have to add the new port version that supports ge 9.0.