configuring programs while making packages

[Martin J Hooper]

Reading through and following this thread on making packages for Ubuntu:

http://ubuntuforums.org/showthread.php?t=49216

I have two of the three packages that I want to package for myself 
sorted but the other one needs parameters adding to the configure script 
before it gets packaged.

How do I do it?  It needs --prefix=/usr passing to the configure script.