So after a lot of searching, trying and failing I've finally got the recipe down for creating a COM visible .net dll file, signing it and installing it (via cab and an exe) via IE such that you can use the control inside IE.
Problem now is, it won't run at the default IE security level (Vista/Windows7). I got a thawte Authenticode cert and signed the dll file, the exe installer AND the cab file (sheesh) and when the cab runs in IE it does say 'this is signed by blah blah' and the UAC has the 'trusted cert' look to it and the installer runs... and then the control doesn't work. If I change the security level down one notch to 'medium' instead of 'med-high', now it runs (after again mentioning 'there is an activeX control here that may do bad things' in a small little tool tip.
Wth, I thought that with Authenticode that stuff will run in IE w/out needing a change in security level.
Help, Sam