How to Reference UNSAccount view (or custom view) in request properties?

I have a custom request that uses request properties to select account in target system (common scenario to enable\disable\change password request).
Unfortunately I can't create a request property that references UNSAccount - when I extend ShoppingCartItem and choose "Foreign Key" as new column type, I don't see UNSAccount view in dropdown list. Although I can see Department view.
I think that's because of different values in DialogTable:TableType for UNSAccount and Department (P vs V).
I tried to create a custom view to wrap UNSAccount but still no luck ( DialogTable:TableType = R) .

I can think of two ways

1) create separate request and request properties for AD, Exchnage,..., UNSAccountB

2) customization of web portal to display popup window for a specific product  

Is there a better way to achieve my goal?