By object do you mean the actual object or just the image/animation linked to the object?
Either way, you can use the move object to action part or you can use the to() Lua script function.
If you want to use the move object to action part, what you should do is something along the lines of this...
move object x to x/y position over x time
pause for x time (same time or greate than you specified in the move object action part)
jump to action part #1
that's more or less how the action parts should look. insert those into a called by other action type action & call it as needed - don't forget to manually stop that action with the quit action action part when you no longer need it to loop.
This is almost it (I didn't know there was a pause function... I only ever thought to look for wait or set timer...).
Only it doesn't cooperate...
I put in:
move object by x 100
pause
move object by x -100
jump to action part #1
What it does is move by 100, pause for nothing near the amount of time I've set, then continue moving towards positive x indefinitely.
Edit: Eureka!
move object by x 100
pause
move object by x -100
pause AGAIN (for 0 ms, but whatever, it works)
jump to action part #1