Loading Balances for Asset Recon Account Using OASV

We need to upload G/L balances in the reconciliation accounts for asset accounts. We are using tcode OASV for that purpose and need to show the balances as beginning balance. What is the way to do that. I am uploading the balance with a posting date in period 1 of 2009 and it shows as an entry in period 1 of 2009 when I run the GL account balance report. Would it make more sense to upload the assets in special period of 2008. Would it show as Balance Carry Forward in that case? It is just few accounts so do not want to use LSMW.

I tried to do the OASV entry in period 14 so the balance is shown as carry forward from 2008 but for some reason the system defaults to period 13. We use 13 periods and 3 special periods. Why is system defaulting to period 13. We have postings in period 13 so want to do it in period 14 it is the only activity in that period or post as a beginning balance in Period 1, 2009.

Please let me know how can I do that.