I don't know about the EU, but for North America Tesla uses a proprietary connector on their vehicles which is different from the J1772 or CCS or CHAdeMO connectors found on US market EV's. Even if you can mock up an adapter, I believe these stations track the VIN of the car it is charging, as Tesla has also been tracking owners' Supercharger habits to see who has been abusing the privilege of "free charging for life" which can only be done if they know which car (by VIN) is charging where and when and how often. So I imagine that it would reject a charging attempt by a non-Tesla vehicle.
Tesla has been in talks with a few manufacturers (primarily Nissan) over opening up access to their SuperChargers but so far nothing has come to fruition. Tesla is already having overcrowding problems at some SuperCharging locations and sharing access with non-Tesla vehicles will only make that worse.