That won't work. Half of the deal with facing is that you can be facing West but moving North in order to not expose your backside to the monster who you will pass.
I just recommend that if someone presses a key, you treat that like a spacebar press, but add a facing arrow at the same time.
Here are the facing rules:
http://www.d20srd.org/srd/variant/adven ... Facing.htm
Under the section "Attacks of Opportunity" look at the middle diagram. I recommend how MapTable could handle that is to have the user click the pog in the first square. Before moving the pog out of that square, they press "8" on the numpad. An arrow facing UP appears. They move to the end of their movement and let go. All spaces in between have an up arrow. (By the way, I use the "show last move" quite a bit as a GM. Having an option to have it ALWAYS show would be awesome)
Let's say now, they do the same move, but after the first three squares, they face EAST and move two more squares.
Then, to handle that, they would grab but not move the pog on the first square and press "8" on the numpad. Then, move four
squares east and on this square, press "6" on the numpad. On the three squares before it, an upward facing arrow is shown, but starting on this, fourth square, the arrow swaps to facing right (east) and then they move another square over and let go. The new square shows them facing east.