Historical Fixed Assets to Tracked Assets Conversion

I am in the process of implementing OAT for a client and this is a fresh install of OAT. The client has been a user of Fixed Assets for a long time. The Operational folks would now like to track their assets by location and customer. Today they have Fixed Assets that are created but not tracked by Serial number and hence Operations has no use of the Fixed Assets. Once we implement OAT we would have all the Operational Requirements satisfied to large entent. My question is how do we get those assets in Fixed Assets and convert them