Is it possible to create a type extension to update an interaction property by name?

I want to create a new method and use it like...

InteractionManager.SetValue(interactionKey, propertyName, newValue);

When I create a type extension, I see there is a InteractionManager method named SetProperty(). However, it requires a "source." I'm not sure what the source would be in this case or if this is even the right approach.