There's a cute book about this called 'the brain that changes itself' which covers a few software projects that help people with strokes or other damage recover some kinds of brain function (and the book also talks about hardware that sorta does what you're talking about for the blind).

It helps if you're not using the brain part, though, I"m not sure you can just get it to happen otherwise. There's a controversial experiment that's described in the book, in which monkeys had various nerves to their fingers severed and lived in that state for years to induce the 'brain map' for an adjacent finger to take over the 'unused' real estate in the brain.

Also, the very tragic phenomenon of 'phantom limbs', which happens when amputees insist that they feel pain, itching, or other awareness of their missing limbs, seems to be related to a sort of miswiring in the brain similar to what you're describing and is very difficult for sufferers to live with.

i just read a section on neuroplasticity in pinker's "the blank slate" which cautions the concept's overuse as another instance of the notion that humans don't have a nature. he talks about the remapping process, and why it works when it works, and why it doesn't often.