Hi kpenigar,
As far as we understood your problem you have two options to solve it:
1. Register the three needed assemblies in the GAC. They are: 'Microsoft.Office.Interop.Excel.dll', 'Microsoft.Vbe.Interop.dll' and 'Office.dll'.
2. Deploy the three assemblies in the same folder where your other extension assemblies reside. This is the way we do it here, so we kind of recommend it.
If you have any other questions do not hesitate to contact us.
Sincerely Yours
Support Team