Using a reference type with an ObjectDataSource parameter

I've got a subclass of Parameter that I wrote to work with ObjectDataSource. It's supposed to allow for interacting with services that take in reference types as arguments. However, I'm finding that the associated bound controls are rebinding on postback because Parameter.UpdateValue does a .Equals to see if the value instance has changed. I can overload .Equals on all my objects, but the parameter would still fail on other libraries' types. However, I can't override the behavior in Parameter, and I do not see any place in ParameterCollection or DataBoundControl where I can change the behavior. Has anyone tried to accomplish something like this, and if so, could you provide some guidance as to what I am missing?
...