I had to refresh myself on the function of the 253. Essentially, it creates a normally open circuit for the isolated track section. When the train motor stops within the open (unpowered) isolated block, it trips a bimetallic strip that closes the track power circuit to get the train moving again. Then, the bimetallic strip cools and opens the circuit again.
So what you need to do is add a latching relay between the transformer track power terminal (A) and the isolated track section. The relay is closed by the control rails of the 022 on the right, and opened by the control rails of the left 022. When the relay is closed, track power flows through the relay and the train travels west without stopping. When the relay is open, power does not flow through the relay and the circuit defaults to the function of the 253, train stops heading east, before moving again.
A spare 022 switch motor could be used as a latching relay. I can draw something up tomorrow for it.
