R61i - no touchpad: can I install one? (7650-E8G / NG1E8UK)

[ShadowWar]

We've bought an R61i for a client, opened the box and discovered that it doesn't have a touch pad. The client doesn't want it but we're having problems sending it back to the supplier, even though we're happy to pay a restocking fee.
Does anyone know of an official Lenovo part which would add a touchpad to the laptop? Comments on this forum suggest that some models of the R61i have a touch pad which implies the connector may be on the board. Without opening it (I don't want to invalidate the warranty if there's a chance someone will just be able to tell me before I need to open up the case), does anyone know if there's a reasonable chance I can get a touchpad working on this laptop? If you can give me a part number that'd be great!
I don't want to go down the route of an external USB device, mouse or docking station.

Thank-you

[fasterbybike]

You should be able to find the part you need to order on this page. The page seems to indicate these are CRU's which I'd assume will not invalidate the warranty. However, you should check when you order the part.