Theres already an existing tactic for this -- can be found through search easily. basically though its--pull the 2 mobs on guard to the top of the ramp, kill guards. Rider will decend but not attack. dragon will fireball from the sky. Grounding totems, fire resist and move in. Rider will be in the middle of the platform, dont go into his aggro range. Blast the dragon in the air while moving your guys out of flames and throwing groundings to avoid the direct damage from the fireballs. When the dragon is at 30% it lands, manouver the dragon with your tank (or designated shammy) away from party so they dont get hit by the flames it breathes and finish it off. Attack the rider who you have avoided aggroing who is still standing there and thats it.

You have no shammys though so youre going to be taking direct fire ball damage. thats an ouch. However use what fire defences you have.
Personally though I find this boss such a massive pain I just leave it out. theres absolutely nothing it gets you which wont be replaced very soon. Too much trouble to bother with at <62 level imop. Go in at 64 if you hate unfinished business and pwn him.