The current light fixture is fed from regular AC wires in the ceiling and is controlled by a two-way dimmer. Since the wiring is not accessible, the new fixture has to be controlled by a wireless method and the dimmer has to replaced with an ordinary two-way wall switch. All supply voltages will have to be derived from the AC voltage feed in the ceiling. Therefore, all power supplies and dimming controls need to be part of the fixture.
The diagram below shows the outline of the light fixture.