Oh, good. It's a level 1 power. Thunder Hooves Rage.
Oh, bad. It grants +1W when attacking the creature you went through. And so is bulit around the idea that you -won't- be charging the creature you went through. You keep leaving off these important details. (also: Cheese shop).
It doesn't matter; the orignal Roundabout Charge doesn't exist any more. Does anyone look at the rules compendium any more (including me)?
Roundabout Charge: When you charge, each square of your movement need not bring you closer to the target of your charge, but you must start the charge at least 3 squares away from the target.
So no, it doesn't let you start adjacent to the target and charge through it to attack on the other side. It -does- let you abuse Thunder Hooves Rage by starting 3 squares away from the target and charge through it to attack on the other side.
If RC still had all the noise about "closest square", then no, it wouldn't work, but it's not worth arguing since that version of Roundabout Charge isn't even a valid feat any more.
But the rules for Charge still do say that each step has to bring you closer to the creature. These rules trump IMO and by following RAW, Thunder Hooves Rage does NOT allow you to charge thru someone, turn around and smack them. You could use a normal move to pass thru them and attack them w/the power's +1W damage or you could charge them and not use the daily.
It WOULD allow you to setup an opportunity to, if you had enough movement for the trick, to move thru them, hope they miss their OA on you, and charge back in. That would require a move of 6 w/o Roundabout and 8 w/it. Or hope you have someone in the party w/an at will of the "can't take OAs" variety

BTW, THR says nothing about the character gaining insubstantial or that the enemy wouldn't get an OA against you when you come out the other side and try to move beyond that first square.