So a couple of minutes ago i had a massive lock up on my laptop and realized i could not get the Magic SysRq (see here) combination to work.

lets first make sure that your kernel is configured for this :
cat /proc/sys/kernel/sysrq
should equal “1”

after some testing, here are the simple steps to get it to work on a laptop that maps SysRq to a function key:
step one : press and hold the alt key
step two : press and hold the Function key (Fn)
step three : press and hold SysRq function key
step four : release Function (Fn) key
step five : press magic sequence as needed.

done.