Quickshooting with guns has been done before, 1sh0t2killz has figured that out
here, in his psycho hero.
It registers an event for the current weapon, and uses a modifier to reduce the length of player data values for Delay and M_Delay.
The code is a little complex, but it should be a fairly straightforward rip.
The
'Veronika' style secondary fire rip is a little more involved.
It registers a forward to catch when a player presses attack2. This calls the launch_nade function, which calls a few other dependent functions you will also need to rip (ammo_hud, particle trail). And of course the vex statements that involve collision detection and damage.
Jill has this pretty cool
rocket launcher in mvc2, maybe something like that...I retooled the
bazooka hero, to work like this back in the day. Instead of calling a function like "make_rocket" once, you can call it using a set_task and make it execute multiple times.
Good luck!