PS/2 Touch Screen and Embedded Controller

am trying to get a PS/2 touchscreen working using a 2.4 kernel based on
Redhat Enterprise WS3. The touchscreen controller sits behind an
embedded controller from National Smeiconductor, part number PC87591.
The embedded controller has in it an i8042 keyboard mouse controller,
with the ability to mux 4 PS/2 ports.

Currently, I have an X windows drivers module that communicates with
the touchscreen controller at startup using /dev/psaux. It sends
configuration commands down, and receives correct ACKs back (0xFA).
Also, when it sends the command to get the model touchscreen
controller, that is correctly received. This is all verified in the
logfile for X.

The file /proc/interrupts shows increasing interrupts for psaux (IRQ12)
when X is starting up. However, after X starts, I do not receive
interrupts from the touchscreen, i.e., pressing the stylus on the
screen does nothing.

I would like to point out that this all works under an ACPI enabled 2.6
kernel. What could ACPI be doing to the embedded controller to get
interrupts to work that I am missing? Suggestions?

Thanks

Steve