Hmmmmm....
Something not so easy I though of, is using Kegetys Spectator script.
Instead of having a respawnAsSeagull, put a base respawn, but, with a trigger (repeatedely, condition : not alive player, on activation : [player] exec "spectator.sqs"), start the spectator script once the player is dead.
Modify the spectator script so that it exits and close the dialog (and destroy the camera) when a global variable is set to true.
The spectator script is a script looping indefinitely following the camera target.
In the begining of the loop, put :
?stopSpectator:goto "ExitSpectator"
at the end of the spectator script, put
#exitSpectator
camDestroy _deathCam
closeDialog 2343534
stopSpectator=false
; use correct dialog ID
exit
So, whenever a player dies, he will be put on spectator mode, unable to move, ie, he is "dead".
When you want your respawn "wave" to occur, just set the stopSpectator variable on the server to true, then publicVariable it.
Every "dead" player (ie in spectator mode) will get out of spectator mode and will be able to control their player, ie the are "alive". setPos them to a correct location (assuming you put your respawn areas in such a way that dead players can't be killed a second time while in spectator mode).
Could work, but a little tough in handling client/server variable state.
Whis'