Extension PriorityAsString not working on RT 4.4

For priority field, a simple ‘High’, ‘Medium’ and ‘Low’ (vs 1-99) will be more applicable in my environment. After search google, I discovered that the there is a extension called PriorityAsString. After I tried to run ‘perl Makefile.PL’, I got the error message below:
**** Error: Your installed version of RT (4.4.0) is too new; this extension only works with versions older than 4.4.0.

How could I workaround this? Anyone know any other method to achieve the same result, i.e. only 3 category of priority? Thanks.
Best regards,HC Mah