Changing an installer package

I'm trying to install some software and it won't let me because it says that my primary language for the system isn't English (it is, though). Is there anyway to make the installer bypass this check so that it will install the software?

 

The solution was to put another language in my international preference pane and make sure that English was the first in the list.

My general question has more to do with how do you go about taking a .mpkg file and editing its contents so that it wouldn't do the check.