I don't have the game open atm so I can't check->copy->paste, so this isn't guaranteed, but it's really simple so I'm pretty sure it's just this:
/cast [nomodifier] Mark of the Wild; [modifer:shift] Thorns; [modifer:control] Gift of the Wild
I use the SmartBuff addon to buff myself. Whenever I scroll the mousewheel up or down (which I do all the time zooming the camera anyway) it applies whatever buffs are within two minutes of expiring, as long as I am in caster form. It also gives nice warning text across the top of the screen, at 120 seconds, 60, 30, something like that, which is handy if I'm in feral form for an extended period of time...nice little reminder.