bind mouse3 "toggle viewmodel_fov 70 .0001 ; toggle r_drawviewmodel 1 0"
bind KP_END "r_drawviewmodel 1; viewmodel_fov 70"

bind KP_PGDN "r_drawviewmodel 0; viewmodel_fov 0"
binds KP_DOWNARROW "r_drawviewmodel 0; viewmodel_fov .0001"

Works pretty well.