How to open the combine doors : first open the dev console. Next input this command :
bind e "+use; ent_fire !picker unlock; ent_fire !picker open"
then hit enter. Now when you press e, you can still use objects but the combine doors also open.
Replace 'e' with anything else that you want.
If you want a designated command just for opening them, use this instead:
bind e "ent_fire !picker unlock; ent_fire !picker open"
And again, replace 'e' with anything you want
Thats how to open the doors. Its hard to find information on it.