It's a Grab
If you're physically taking control of another creature and moving them around the battlefield, I'd say that that's exactly what a grab is.
The only difference is that you're using a rope instead of your hands so that you don't necessarily need to be adjacent. It's up to you as DM to decide whether that's different enough to disqualify it. If your play group uses a fairly simulationist style, like mine, then that seems plenty close enough to me.
From the Rules Compendium:
Standard Action, Melee touch
Requirement: You must have a hand free.
Target: One creature that is no more than one size category larger than you.
Attack: Strength vs. Reflex
Hit: you grab the target until the end of your next turn. You can end the grab as a free action.
Sustain Minor: The grab persists until the end of your next turn.
I don't see any reason to change any of that, except perhaps changing the attack from strength to dexterity or intelligence to represent the different challenge of tying a rope. Require that the rope be tied to the wizard by someone adjacent to them to satisfy the "Melee touch" requirement. Require that the person holding the rope have a free hand for the rope.
Move a Grabbed Target
Action: Standard action
Strength Check: The creature makes a Strength check opposed by the Fortitude of a target it is grabbing. The check automatically succeeds if the target is a helpless ally of the creature.
Success: The creature can move up to half its speed and pull the target with it. The creature's movement doesn't provoke an opportunity attack from the grabbed target, but the movement otherwise provokes opportunity attacks as normal.
Once again, don't see any reason to change any of this. This assumes that you're adjacent to the target the whole time, so you'll have to impose a range on it to account for the rope. It says that the attack automatically succeeds against a helpless ally. I would be comfortable considering an ally who is cooperating as being helpless for this purpose, since they won't resist at all.
Far from being unbalanced, 4E's action economy makes this seem not even worth it.
The initial grab is a standard action, so someone has to give up an attack to make it. It might not succeed, although you can rule whatever penalties or bonuses for the attack you deem reasonable. Keep in mind that tying a rope in the middle of battle is not necessarily trivial.
After the initial grab, whoever has the rope has to give up a minor action every turn to sustain it.
Furthermore, moving a grabbed target is a standard action, so whoever has the rope isn't making any attacks.
Also, if your PCs are doing clever stuff like this, and you feel like it's too powerful, have them fight some clever enemies. It's not that hard to cut, burn, or otherwise damage a rope. They might not even want to sever it though. Perhaps instead they can use it to their advantage. Maybe an enemy could make a strength check to grab the rope away from the party member, and drag the Wizard off a cliff. Not a lethal cliff, of course. Not the first time.
I would suggest you not even go here for the same reasons as Wax Eagle. If you apply it here, you're going to have to start applying it other places, and it's going to be a nightmare.
That being said, if you want to pursue the idea of one of your characters 'throwing' the wizard, this question about throwing a halfling might be helpful.