Chronic_bind "mouse5" "slot1; slot2"
bind "mouse4" "slot1; slot3"
this is odd? is this really working out well for you?
also, how exactly does that work? does pressing M4 equip you with slot3, if slot1 was already equipped, and vice versa?
this does not work exactly the same, i think:
alias wep1 "slot1;r_drawviewmodel 0;bind mouse4 wep3;bind mouse5 wep2
alias wep2 "slot2;r_drawviewmodel 0;bind mouse4 wep3;bind mouse5 wep1
alias wep3 "slot3;r_drawviewmodel 1;bind mouse4 wep1;bind mouse5 wep2
bind 1 wep1
bind 2 wep2
bind 3 wep3
bind mouse5 wep2
bind mouse4 wep3
edit:
when you equip slot1, M4 and M5 become slot3 and slot2,
when you equip slot2, M4 becomes slot3 and M5 becomes slot1,
when you equip slot3, M4 becomes slot1 and M5 becomes slot2.