Middleware settings to map CRM Z table fields with ECC material master flds

Hi,

We want to create  a Z table in CRM,this table willl have 2 fields External Material Group and Old Material Number.These 2 fields in CRM table are corresponding to same material master (MM03) fields in ECC.The changes to these fields done in ECC material master should be updated in CRM Z table.

I want to understand the middleware settings I need to do in order to map the ECC and CRM fields.

Thanks in advance for your help

Swapnil