2ndary ledger

Hi, We have a currently active Ledger and we need to add a 2ndary ledger for tax reporting.  We are doing the journal transfers at the subledger level.  We do not want to go back 7 years to start the 2ndary ledger when the primary was created.  We want to create the beginning balances and then start with the activity.  How can we populate the beginning balances for the 2ndary ledger?  Do we need to do this first and then run the concurrent program to transfer XLA data (SLA Secondary/ALC Ledger Historic Upgrade)?  Thanks!