Adress "hidden" parameters in vst Plugins

Dear all

Some plugins have parameters that are not reachable through the standard method of sending parameter-number and value. They also do not get dumped when i send the "params" message.

But those parameters are adressed in snapshots. By saving the state of a plugin, changing preset und restoring the state via snapshot those parameters are set correctly.

Is ther any way to adress them directly? Maybe there is some kind of Max/MSP-External or some method that i do not know of to get to those parameters?

One example is the FX-type-menu in Arturia plugins. You can set all parameters of all Effects but you can not chose what effect should be active in each engine. I really would love to be able to do that...

Thanks in advance for any help

Noa