I have looked into this extensively. (i would say too extensively) but here are my conclusions.

1. the easiest route to go is to purchase a backlit topcase from the 2.4gh macbook. It is about $200 right now. Everything else is plug and play. Both logic board has a built in connection for the backlit keyboard. It just in the 2.0 the keyboard does not plug into it. (since it is not backlit) thus if you buy a 2.4gh top case, it would work. part number is 661-4944

2. MBA is a no go, it is basically engineered so specifically to fit the small enclosure that it would be close to impossible to transplant it.

3. MBP unibody has a different layout. (two fans etc.) and just by looking at the teardown, the keyboard connection to the logic board is at a different placement. and it's not like a cable where you can move around or extend.

In conclusion, if you really couldn't let this feature go, spend $200, or wait a little more. Remember you can also try to sell your non-lit topcase for probably $170, which makes this a $30 upgrade. (well worth the money) The only problem with that is there are not as much demand for unibody parts right now. most people go to apple warranty at this point, but in time it would get easier.

let me know if i could be of help,

John