It is possible to replace the keyboard on your 2008 MacBook Pro with the backlit keyboard from your 2011 MacBook Pro, but it may not be a straightforward process. The main issue is that the keyboard connector on the logic board of the 2008 model may not be compatible with the backlit keyboard from the 2011 model. Additionally, the logic board on the 2008 model may not have the necessary hardware to support the backlighting feature.
If the connector on the logic board of the 2008 MacBook Pro is not compatible with the backlit keyboard from the 2011 model, you would need to find a compatible keyboard that is designed specifically for the 2008 model. Alternatively, you could try to modify the connector on the 2011 keyboard to make it compatible with the 2008 logic board, but this would require some technical knowledge and skill.
Even if the keyboard connector is compatible, you may still need to modify the firmware on the logic board to enable the backlighting feature. This can be a complicated process, and it may not be possible without specialized tools and expertise.
In summary, while it is technically possible to replace the keyboard on your 2008 MacBook Pro with a backlit keyboard from a 2011 model, it may not be a simple or practical solution. You may want to consider other options, such as using an external keyboard with backlighting or upgrading to a newer MacBook Pro with a built-in backlit keyboard.