How do I get EXSLT support in Saxon-HE?

I have a bunch of XSLT files that I need to process against some XML files. I cannot change the XSLT files as they come from a 3rd party. The XSLT's are version 2.0.

I'm on Mac OS X 10.6 and it looks like Saxon-HE is the only XSLT 2.0 processor available.

Most of the XSLT's work fine, however, some give errors regarding missing functions, specifically month-in-year() and other date/time related functions.

According to http://www.saxonica.com/documentation/extensions/exslt.xml regarding EXSLT:

These extensions are available in Saxon-PE and Saxon-EE "out of the box". They are not available in Saxon-HE

Is there anyway that I can use the EXSLT functions with Saxon-HE?

I'm happy to move to another tool/processor if that would work.