Here are some precisions (taken from j89hw.txt) :

$600005 -W Turn off OSC1 (and the CPU), wake on int level 6 (ON key) and ...
:7-5 -
:4 ... int level 5 (programmable timer)
:3 ... int level 4 (link)
:2 ... int level 3 (OSC2/2^19)
:1 ... int level 2 (keyboard)
:0 ... int level 1 (OSC2/2^11)
Note: Make SURE int level 6 is acknowledged before writing $00 to this port...

Grayscales use the AI1, and AMS >= 2.07 uses the AI3 for the clock, and your program uses the AI5, so you should write 0b00010101. The code posted below waked up on AI2 too. I don't know if it's important or not...