How to bind a key to "weapon up" command?

[old.Guru]

I fugured out that impulse 12 binded to a key let you switch weapon down, e.x. if you holding RL and press button, which is binded to impulse 12, you will be shooting from grenade launcher(supposed u have GreLauncher).
But, which command let you bind a key to weapon up?
PS. Sorry for my lousy English

 

[old.[RSi]Skippy]

Impulse 10

Skips