I want to install my addin to HKLM rather than HKCU so that all users can use
it. I can make the necessary registry changes to the setup project and
install it as administrator and it works OK for all users - but only if they
are administrators.

There is conflicting evidence on the web: this MS article tells you how to
do it - so you would figure it was supported:

http://msdn.microsoft.com/en-us/libr...nf orAllUsers

but I have seen Ken Slovak responses suggesting this is not supported...eg:

http://help.lockergnome.com/office/V...ict942994.html

Can anyone give me a definitive answer on this? Is there any way out?

I hope so because it will cost me a 6 figure sale - not to mention the six
months of work thats gone into it. Help!