Resto Shaman is a bad healer in this combo. PvP gear aside, he's very vulnerable to lockouts which means that even in the best of cases your Mage is vulnerable. You have some CC, but not enough to ensure that he doesn't get exploded in that time span. Druid or Priest (yes, the classic RMP) would be a better team because they can ignore or bait lockouts much more effectively. With that said, you do have a ton of burst to use it. You should also try to ***** with their heads - you're playing a somewhat nontraditional combo, so use that to your advantage.
Try having your Shaman start in Ghost Wolf with Water Shield on instead of ES (give it to the Mage and have him start invis). And, well... rush them. It won't be instantly obvious that the Shaman is the healer of the team and you should have a rather hefty amount of burst if you can catch them offguard. You should be the second person visible and the Mage should absolutely be the last person to appear; you want them to latch onto you or the Shaman at all costs, as the Mage is the weak link. Elemental Shamans are usually quite good targets for Hunters to aim for, so if it's not obvious that the Shaman is Resto he may be targetted... and since he has a good bit of Resilience (compared to the Mage, anyway) this is probably your best-case scenario.
You may also want to consider not using AI, so that the mage comes as a real suprise. You want them to be thinking double Rogue or very sneaky druid, not Mage. Bloodlust as soon as you engage and try to annihilate them between CS, Kick, Blind and Poly. Sap is nice but if you can't get it off don't sweat it - you want to be launching yourself into their throats so they don't have time to analyze, and even if you sacrifice your CC it's worth it.
You almost certainly want to nuke a DPS target and CC their healer(s), although I'd imagine you already knew that. Communicate on vent, etc, and try to organize a pattern of CCs for future reference... or just tell them what to do. "CS Pally now!" or whatnot.