You seem to be expecting huge transients!
The data sheet doesn't specify how the 'stages' of current control are selected, it may be by monitoring the voltage across the Vin and VP pins in which case applying steady DC will stop the internal circuits working and you would have to rely on the dimming control to limit the LED current. VP is normally connected directly to the LED positive supply so if the drivers work by applying less than VP to enable the switching devices, you may find they are turned an all the time.
You need to experiment, what you propose is well outside the manufacturers design recommendations but might still work.
Brian.