You can use SEXPS to get the warp effect you want without actually warping.
Step 1: trigger the false warp cycle on an event cue.
Step 2a: Use ship maneuver under coordinate manipulation to control the speed of the ship in the warp cycle.
Step 2b: Activate the warp sounds using play-sound-from-table. The warpout sound you are looking for is Rev1 or sound #50 in the tables.
Step 2c: Display the 'warp icon' in the hud using the hud sexps.
Step 3: Open a warp hole, if you want, in front of the player ship using a sexp.
Step 4: Break warp. By cancelling ship maneuver, closing the 'warp icon' and playing the aburn_1f sound using play-sound-from table. This one is #47 in the sounds .tbl.
By doing things this way, you never run the risk of the player leaving the mission and the game ending, and it prettymuch looks like the real thing.