Making alternate fire modes?

[Mengo]

In a wad I'm making I have 2 plasma rifles, where one is used as an alternate fire mode. Both are sisterweapons and one has the +POWEREDUP flag, but how can I make the player able to switch between them without having to switch items and use an inventory powerup?

[SaladBadger]

you don't need +POWEREDUP if you want alternate weapon forms like Strife. simply setting the SisterWeapon property is enough.