Here's a basic solution(i'm assuming you mean the z position?)
Your 3d object has a setting > Properties > Settings > Z (underneath Depth)
This will propably set at zero, unless you have already changed it.
Give your 3d obect a private variable called 'zpos', and set its value to the objects initial 'Z' setting.
+ System: Start of layout
-> 3dthing: Set 'zpos' to 0 (or whatever its currently set at)
+ Button: On Button clicked (I'm using a button to move it)
-> 3dthing: Add 10 to 'zpos'
+ System: Always (every tick)
-> 3dthing: Set Z to 3dthing.Value('zpos')
So everytime you click the button, the 3d object will move 10 units.
Hope this helps