Posting to G/L account in Next period & Opening balances

We need to post to G/L accounts for new Company code

1) During month of February , Can we post to GL accounts(FB50) with Posting date in January? --> if we have Period 1,2008 open in OB52 ( FROM Period 1,2008 TO Period 2,2008)

2) Is there a way that Opening balances can be posted to the G/L account other than using FB50/F-02. There are only 10 G/L accounts ,so I don't want to do it programmatically.

Please reply at the earliest.

Thanks