The ERNW CVSS Calculator is now availabe from our Website for free.
Grab your copy here:

http://www.ernw.de/content/e15/e26/e914/ernw-cvsscalc_ger.zip 

This version supports CVSS Version 1 and 2 and has some useful
functions to work with CVSS in pentest reports, so just take a look.

If there are any question about the usage, just read the tooltips, you
will find all the help there.