1 Animation, 2 actions - How to?

Hi, So all my character animations loop, except the sitDown one. I can either set to PlayOnce or ClampForever. Regardless of which one of those I choose, how then would I following this, set about playing the sitDown animation in reverse, so I can simulate a stand up? The tricky part is that sitDown is presently at the end of its frames and so making it Speed= -1 and pressing play doesnt work (both the computer and I lose track of which way is backwards) so I need to play it backwards, but then if its speed is -1, do I Animation.Rewind() it or Just say Speed = -1, Play...because that is not having the character stand up..The sitDown animation is on Layer 2.