Change in Depreciation useful life as well as rate

Dear SAP Guru

I want to change useful life of assets and want to give the treatement as per accounting standard 6 which states, " Where there is a revision of the estimated useful life of an asset, the unamortised depreciable amount should be charged over the revised remaining useful life. "

We have number of assets for which we need to take this change in to consideration.

How it is can be done in SAP. What are the steps to do the same in SAP?

Kindly advise.

Regards,

Ashish