Hello,
You cannot do it yourself. But being honest, your hosting company should really consider upgarding. Leaveing that much outdated versions of basic server services is like opening the door for those scams that want do destroy sites and servers

If you consider a live shop then it is worth the effort even to change your hosting company not to loose money or business later on...
The other solution is to make the script compatibile with your version, but this would require to rewrite some of the parts of the code which we cannot afford to do right now.

I can suggest you to try out olderest version of Boss Cart, which might not have this problem but this would be downgarding...
Best Regards,
Piotrek