Alternative Icon for File Associations

So, I've thinapp'd Orca, the, I can't live without it, MSI editor from the Microsoft SDK.

Orca, being an MSI editor, associates itself with .msi files.  You right click on an msi and you get Install, Repair, Uninstall, Edit with Orca.

No Probs, thinreg handles that very nicely.

Problem.

All .msi's now have Orca as the default icon instead of the default icon from msiexec.exe

Is there a way to prevent thinreg from overwriting the existing DefaultIcon for the file association?

or

Is there a way to specify the default icon for FileTypes?

Aesthetics can make all the difference to the end user experience.