You can do it by giving the to-be-mindtricked NPC a mindtrickscript that affects the other NPC to do as you would like him to do. That's no problem, and it's very easy. Just remember to set the mindtrickscript to null, since you can have undesirable results if you forget that.
Set the dude to cinematic behavior_state, and he will surely forget pretty much everything going on around him... Or
you can turn off various booleans like ingore enemies, ignore alerts and such. Take away his weapon... Just turn off everything that might look useful. It might still not work, but you can try.