Problem solved, partially.
The problem was that when you touch the pad, it sends an X and a Y signal - ie the controller assigned to X sends its position, then the Y controller sends its position. Since Resolume listens for the first message, it was only picking up the X axis.
The solution was simple - in the MIDI program mode on the Entrancer, disabled sending of all the controls except the Y axis (CC#13), then taught Resolume that control, then re-enabled all the controls again.
Now the problem is that Y axis doesn't match the effect I'm assigning it to - it's inverted. Is there any way of inverting a MIDI program in Resolume ie make 0-127 act as 127-0 instead?