Either directly use the Python 2.4 interpreter to run it, or modify the programs she-bang line to point to the interpreter you wish to use.
Note that there's many things in common use in recent python (any
/all
, the 1 if 2 else 3
syntax, as well as major stdlib and language changes) that may cause your program to experience difficulties.
It's also worth noting that a lot of the common 3rd party modules require at least 2.5 and some of those are even dropping that and only guaranteeing 2.6+ compatibility.