Simple as that say you are a light assult with C4 and the new knife the knife would be in the 4th slot and in adition to pressing B you could press 4 (or for the second time to activate it. Just a little polish that I would like. Maybe even making it look different when activated.
If you check the keybinds on PTS, there's already a knife slot set up, actually. If I remember correctly it's currently set to pressing 8, but you can easily rebind it to something closer (I put it on ~, as PS2 doesn't have a console that would normally take up tilde).
