wrkdirprefix default?

[Anthony M. Agelastos]

Hello.

Sometime back, I posted a message mentioning that I planned on  
installing OpenOffice once it reached 2.0 status on my FreeBSD  
machine using a nonstandard wrkdirprefix path (original email is  
shown via the below link).

http://www.freebsd.org/cgi/getmsg.cgi?fetch=184696+187981+/usr/local/ 
www/db/text/2005/freebsd-questions/20050918.freebsd-questions

One reply was that I can use

env WRKDIRPREFIX=/myotherlocation make install

This is fine for installing it, but I was wondering was there a good  
way of modifying WRKDIRPREFIX to always point to this location only  
for OpenOffice.org, that way I can use portupgrade in the future and  
not have to worry about it? I am assuming the best way of dealing  
with this is with the file /usr/local/etc/pkgtools.conf.  assume that  
I could put it inside of the MAKE_ARGS section. What is the most  
optimal way of modifying this file for what I have mentioned above? I  
have read the pkgtools.conf and ports manpages (and am still slightly  
confused) and am running FreeBSD 5.4-STABLE.

If the only way to do this is by modifying the variable on the whole  
so everything is built elsewhere, I suppose that is alright as well.  
If this is the only way, what is the preferred way of handling this?  
Thank you all for your assistance.

-Anthony