Cut off a segment that doesn't matter to you and put it into some sandy soil. Make sure the soil is dry at first, but after a few days start giving it just the slightest trickle of water.

You want it to crave the water. So actually starving it for the first few days will set it up for really wanting it.

Once you start giving it just a trickle at a time you have to wait for it to root. You can usually feel this by tugging on it after a few weeks, but I'd give it about 8 weeks to see if it's really taken to the soil.

Then just grow it along side the other one, and hope for the best.

You won't get 100% growth, but your sure to get 70% or 80%, so you're off to a good start.