I ma writing this from memory, If I mention an interruot source the 953 does not have, ignore it.

here is the recipe for, at least 10, additional interrupt pins.
you can use the keyboard interrupr for 'regular' events, I have done so.
you can use the comparator inputs.
you can configure a timer as a counter and preload it with ffff.
I think you can use the IIC interrupt.

Erik

using the keyboartd interrupt with the correct code you will get an interrupt when the signal comes and one when it leaves. That way you can, for all practical purposes, consider the interrupt 'edge triggered'

Using the compareators as logical interrupt sources you can use them for level or, if you connect the comparator reference to an output pin, you can get the same effect as above.

Using a timer, basically gives an edge triggered interrupt

I considered using the IIC once and believe I found it possible, but other things came up, so there is no more about that.