has released a new version of this coop mission in the BI forums
Now it doesn't need the VOP2.1 addon to be played.
Quote ahmedjbh :
I have made this public, not because it is good, but because I enjoyed making it and playing it, and maybe others will too. If you dont like it, you may give constructive criticism. I have tested it with friends and fine tuned it, and not found any bugs etc
It features the revive script by Norrin (infact I built it on his template file!)
This means when you die, you can either wait to be revived by a team mate or chose to respawn slightly behind the front lines.
In future I will use no mods when editing!