running php4 and php5 on the same box

[Steel City Phantom]

i need to configure both on my bsd machine.  i found a few pages on the 
web that had some general instructions on how to do it, but i was hoping 
someone here could tell me how to do it using the ports collection. 

http://wiki.coggeshall.org/37.html looked promising, but i wanted to see 
what you guys thought first

one requirement that i have is i need to run pretty much all the php 
extentions for both of them.  so if i run php4-extensions and 
php5-extension, what am i going to screw up?