two ways (that i know of) that you could do this:
i assume you've tried editor-placed waypoints, and in my limited experience they can be... well i dunno. i know the feeling you describe, let's leave it at that.
you've got the two 5-man teams outside the truck. the truck has a 'load' waypoint near the groups, and each group has a 'get in' waypoint synchronised with the 'load' waypoint. first step over. if you've managed to get them into the truck, getting them out again should be the same, just in reverse.
the truck is waypointed to where it needs to go. second part over.
here's where i get confused with transport waypoints. you give the truck either an 'unload' or 'transport unload' waypoint where you want the teams to get out, AND each team is given a 'get out' waypoint near the same place, both synchronised to the truck's 'unload' waypoint. that's the last step, and everything moves on from there as usual.
the second, slightly more involved method is using script to do pretty much exactly what's described above, using a trigger at the destination, activated by the truck being present, and on activation calling a script which tells the two squads to get out - syntax iiiiiis (bedges looks up the comref)
group_name leaveVehicle vehicle_name
which works for individual units or groups. personally i would avoid the second option, as i've had problems reconnecting the groups with their editor-placed waypoints after grabbing them with a script and telling them - nay MAKING them do what they're supposed to, the stoopid lil.....
i digress. good luck