Here's an excerpt you could use as well (if for some reason the mod folder has a different name):
REM queries for the exact (/e) String "GoldenEye: Source" in HKLM\Software recursively (/s)
reg query HKLM\Software /s /f "GoldenEye: Source" /e
The problem is retrieving the result of the query.
From there on it's just the value of the install key.
I think on other versions of Windows it wouldn't be the Wow6432Node in between Software and Microsoft\Windows\CurrentVersion\Uninstall\..., so the query is important. But yet if I do it in a For-loop it seems to insert Values for variables in advance instead of on every loop, so I can't do checks what has been returned by the query, so I can only store the key path instead of "1 result has been returned". -.-