No, do not run the installer. Just Copy & Paste the said folder over to your Vegas 6/7 folder. Run Vegas >> goto TOOLS menu >> Select SCRIPTING and there you will see the Quake files ready to use.
The installer is not needed, it puts nothing in your registry it simply drops those files in the scripting folder. So basically you can do the same as the installer does by just Copy & Paste.
Ps: It works great, but it needs a bit of tweaking to get it right.
Here is a Link if anyone else is interested:
http://www.vasst.com/search.aspx?text=quake
=]