alias s1 "slot1;r_drawviewmodel 0"
alias s2 "slot2;r_drawviewmodel 0"
alias s3 "slot3;r_drawviewmodel 1"
bind 1 s1
bind 2 s2
bind 3 s3
in autoexec

EDIT: It appears I was ninja'd by Botmode.

Well it's possible, as long as you don't use Quickswitching or the scroll wheel changing.

Personally I pull my Melee out with 3, so I bind my 3 key to turn viewmodels on and pull out Melee. And my Q and E keys (Primary and secondary) to pull their weapon out and turn models back off.

It's incredibly simple to write up yourself.
Mine looks like this

Simply change to keys to whatever you'd want to use to draw that weapon.

Is it possible to have it so that I can use the mouse scroller? Or is best to use the number keys?

Or you can do this (this will have it so that when you switch, it will change):

bind "q" "switcher"

alias bat_vm_mode "bind mouse1 +viewmodel_bat; viewmodel_fov 76; r_drawviewmodel 1"
alias scattergun_vm_mode "bind mouse1 +viewmodel_scattergun;viewmodel_fov 0.0001; r_drawviewmodel 0"
alias pistol_vm_mode "bind mouse1 +viewmodel_pistol; viewmodel_fov 0.0001; r_drawviewmodel 0"

alias +viewmodel_bat "+attack;spec_next"
alias -viewmodel_bat "-attack"
alias +viewmodel_scattergun "+attack;spec_next"
alias -viewmodel_scattergun "-attack"
alias +viewmodel_pistol "+attack;spec_next"
alias -viewmodel_pistol "-attack"

alias equip_bat "slot3;bat_vm_mode;viewmodel_fov 76;r_drawviewmodel 1"

alias equip_bat2scattergun "equip_bat;alias switcher equip_scattergun2bat;bind 2 equip_pistol2bat;bind 3 equip_bat;bind 1 equip_scattergun2bat"
alias equip_bat2pistol "equip_bat;alias switcher equip_pistol2bat;bind 2 equip_pistol2bat;bind 3 equip_bat;bind 1 equip_scattergun2bat"

alias equip_scattergun "slot1;scattergun_vm_mode;viewmodel_fov 0.0001;r_drawviewmodel 0"

alias equip_scattergun2pistol "equip_scattergun;alias switcher equip_pistol2scattergun;bind 2 equip_pistol2scattergun;bind 3 equip_bat2scattergun;bind 1 equip_scattergun"
alias equip_scattergun2bat "equip_scattergun;alias switcher equip_bat2scattergun;bind 2 equip_pistol2scattergun;bind 3 equip_bat2scattergun;bind 1 equip_scattergun"

alias equip_pistol "slot2;pistol_vm_mode;viewmodel_fov 0.0001;r_drawviewmodel 0"

alias equip_pistol2bat "equip_pistol;alias switcher equip_bat2pistol;bind 2 equip_pistol;bind 3 equip_bat2pistol;bind 1 equip_scattergun2pistol"
alias equip_pistol2scattergun "equip_pistol;alias switcher equip_scattergun2pistol;bind 2 equip_pistol;bind 3 equip_bat2pistol;bind 1 equip_scattergun2pistol"

equip_bat2scattergun

Do you use the scroll wheel to cycle through your weapons? If so, the bind is a little more difficult, and wouldn't work very well with weapons that aren't actually weapons (gunboats). Or do you have it like, scroll wheel up = primary, scroll wheel down = secondary?

I wouldn't say it's better either way, personal preference.

I don't really know how you feel about alternatives but, I was in the same place as you a while ago, what I use know is the mouse wheel to control my view models

bind "MWHEELUP" "r_drawviewmodel 1"
bind "MWHEELDOWN" "r_drawviewmodel 0"

Thanks for the help guys, I'm gonna try and see if any of these work.

bind 1 "slot1; r_drawviewmodel 0; viewmodel_fov 90"
bind 2 "slot2; r_drawviewmodel 0; viewmodel_fov 90"
bind 3 "slot3; r_drawviewmodel 1; viewmodel_fov 84"