usgaap expense difference.

Hello,

We are using a national book for assets and need to use a usgaap assets, I believe we can use a tax book or either create another book to add the assets to fit the need of a paralell book.

But now what we need is to resgiter the depresiation expense this way:

For example I have asset 1 for 1000.00 usd, and this asset , it has 2 years of life for one book (book 1) = $41.67 and 3 years of life for the other book(book2) $27.77 , we need to register the depreciation expense of book 2 completed and just the deprecitation difference to book 1. How can we get this done automatically... Can the SLA be used ?