Mathcad 12 & Refprop (NIST23)

Does anybody have any ideas on how I could get Mathcad and
Refprop (NIST Standard Reference Database 23) to work
together. I was trying to access Refprop through VBScript, but
one of the limitations with VBS is that, unlike VB, it can't declare
DLLs, so I'm stuck.

A previous posting suggested using Excel to access Refprop and
then embedding the Excel program in Mathcad. That seems like
it might be more complicated as well as slow.

I was also thinking C++. I'm not the world's greatest C++
programmer, does anyone have a detailed reference for creating
DLLs in C++, or at least point me in the right direction?

Thanks in advance,
Jonah