The addin contains the following in its Auto_Open

Application.AddIns.Add ThisWorkbook.FullName

This puts the addin in the list in the Add-Ins dialog box, with the
check box empty.
If I close and reopen excel, it's still in the list. This is what I
want as it "installs" the addin for me.

If the addin is then opened manually from another folder, that .Add
statement above gets run and this seems to redirect the addin as being
installed from the second folder, but closing and reopening excel
shows that it's still "installed" from the first folder. This is not
what I want.

What is the right and proper way to "install" and "uninstall" an
addin. In this case I don't have to worry about links to UDF's in the
addin because this addin isn't used for that sort of thing. Can
registry settings be easily changed for any excel version?

Could a small VB6 program be used to launch one or more instances of
Excel to do the uninstalling and installing?

Thanks,

Brian