How to introduce "setx" command on CentOS 5.2

I'm working on a CentOS 5.2 system (I know it's very old, but it's the customer's choice).

I am ruing a program, which inteally performs some setx commands, but it seems that setx is not understood yet by this platform.

Therefore I was thinking to replace setx by export, using an alias, but now a very stupid issue pops up: see followings commands' syntax:

setx   : setx   <variable> <value> // watch the space
export : export <variable>=<value> // watch the equal-sign

Due to that simple difference in syntax I think I can't use alias setx export (at least that's what I think, or can I work around that?).

Does anybody have a simple way to get around this? (for your information, I have already found a workaround, but this is using specific features of my technology, and I'm wondering if there is a general solution)