R12.1.3 Fixed Assets - Additions Integrator

In the near future, I will need to upload around 40,000 assets into Oracle. Currently, we use the Additions Integrator and manually adjust the useful life via the front end if necessary. I am having difficulty determining how to utilize the LIFE_IN_MONTHS column in the fa_mass_additions table after an upload with the Additions Integrator. I have a test file that has 6 assets. 3 of those assets have a life of 3 years and the other 3 have a life of 10 years. This is based on the major and minor categories, of course. In most cases, we would like