Dude, what are you doing getting it into pof stages before you know how you're going to handle something like this?

The best way to do sliding is to use 2 separate extra subobjects - basically just invisible rectangular prisms, each one exactly half the length of the distance you want the object to slide. You then arrange them like this:
/\__ (with the bars being the / and \, and the __ being the door or whatever you want to slide.) The door is the child of the bar that touches it, and then that bar is a child of the second bar which is a child of the ship hull. Each one is then a rotating subobject that can be animated to slide using only rotations.
In the model, you have their default position fully extended - so the doors would be closed in the pof. Set each animated subobject up in the pof as a 'rotating' along any axis, and in the properties field put
$special=subsystem
$triggered:
In the ships table, you would then have something like:
$Subsystem: Door1, 5,0.0
$animation: triggered
$type: door
+reverse_delay: 1000 ;;Time until door closes again
+relative_angle: 90,0,0 ;;How far the door should rotate relative to its parent
+velocity: 10,0,0 ;;How fast it's max speed should be while rotating
+acceleration: 5,0,0 ;;How fast it gets to that max speed
+time: 1700 ;;How long until the game will say the animation is complete
$Subsystem: Door1BarA, 5,0.0
$animation: triggered
$type: door
+reverse_delay: 1000 ;;Time until door closes again
+relative_angle: -90,0,0 ;;How far the door should rotate relative to its parent
+velocity: 10,0,0 ;;How fast it's max speed should be while rotating
+acceleration: 5,0,0 ;;How fast it gets to that max speed
+time: 1700 ;;How long until the game will say the animation is complete
$Subsystem: Door1BarB, 5,0.0
$animation: triggered
$type: door
+reverse_delay: 1000 ;;Time until door closes again
+relative_angle: 90,0,0 ;;How far the door should rotate relative to its parent
+velocity: 10,0,0 ;;How fast it's max speed should be while rotating
+acceleration: 5,0,0 ;;How fast it gets to that max speed
+time: 1700 ;;How long until the game will say the animation is complete
This would make the setup go from this: _ _ __ to this: /\__ to this:
|__ and back again after 10 seconds <- the doors open and then close.