Hmm, for some reason it no longer works! The soldier character is floating in mid air.
Anyhow the method was simple enough, just get the soldier into the correct position relative to whatever you want him to sit on and then use the animation from frames 3710 to 3744 to make him sit down. Getting up again is frames 3828 to 3862.
Been there, done that, got all the T-Shirts!