Brad - MessageBox is output only (OK, mostly - it allows button-based input). This needs to prompt for manual input text - email address. Also - he is using Kix for membership identification (If InGroup). I do agree that we can probably replace the VBS, but suspect its a 3rd party component of the AD Self Service app.
I looked at that function and don't see any controls for presence (minimize, show/hide, etc.) I did a quick look at this but could not find any more information about control options. I'd suggest not minimizing the Kix script and see if that helps.
KixForms would certainly help here, but that would require deploying/registering the DLL. Not as big an issue as you might suspect. I've used a BAT file to copy Kixforms.dll to C:\TEMP, register it with RegSvr32, then invoked the Kix/KF app, and then unregistered/delete the DLL. Hardly took any time at all. User permissions could be an issue with this, however, as users rarely have the needed rights nowadays.
a Rocket Scientist!