Dridzt is correct.
Another option would be to use the /stopmacro command before all of the [mod:alt]-only lines:
Code:
#showtooltip
/cast [nomod] Charge
/cast [nomod] Victory Rush
/stopmacro [nomod:alt]
/cast Intervene
/targetfriend
/targetlastenemy
You may also consider using a second modifier for Charge:
Code:
#showtooltip
/cast [mod:shift] Charge
/cast [nomod] Victory Rush
/stopmacro [nomod:alt]
/cast Intervene
/targetfriend
/targetlastenemy
or having the macro always show Victory Rush (by putting that first) so you can easily monitor its availability:
Code:
#showtooltip
/cast [nomod] Victory Rush
/cast [nomod] Charge
/stopmacro [nomod:alt]
/cast Intervene
/targetfriend
/targetlastenemy