New document with Item Tracking Line

Hi, I have a new document ( Internal Consumption ). This document have header and line. In line is Item . Items have set Item tracking ( SN and LN ) In can assign Item Tracking Line for a line in this document ? I must modify some Codeunits for Reserv an Item. Theese codeunits is for make a reserv for an item an post this document. This document write in : G/L , Item Ledger Entry, Value Entry. Is possible to add new DATABASE in reserve codeunits ? Is very difficult ?? Thanks, IM