A Spy class-specific command
Layout
The basic layout of the disguise command is very simple.
disguise [class] [team]
class Parameter
1 : Scout
2 : Sniper
3 : Soldier
4 : Demoman
5 : Medic
6 : Heavy
7 : Pyro
8 : Spy
9 : Engineer
The reason the classes are in this order is that they were added in that order. As mentioned in Quake World Team Fortress ยง Versions on the Team Fortress wiki, it mentions the classes were added in the order of scout, sniper, soldier, demoman, and medic; then heavy; pyro; and finally spy and engineer.
team Parameter
These depend upon what team you're on.
-1 : Enemy Team
-2 : Friendly Team
Specific Teams
These aren't extremely useful, but they exist. They are independent of the team you're on.
1 : Blu Team
2 : Red Team
Example
Normally, when you disguise as a spy of your team, you undisguise. This also applies to the disguise command, allowing for an "undisguise" command.
disguise "8" "-2"
You're also able to put this into a bind, allowing for an undisguise bind.