I found something that could lead you to the correct answer when trying to do something similar. You will need to create a folder the same way you do to see all of the sales orders, but you will need to filter the results based on the Domain.

This best info I found was "Expressing a search domain (args)" and here is the link(I can't insert links yet)

(doc.openerp.com/v6.0/developer/2_5_Objects_Fields_Methods/methods.html#osv.osv.osv.search)

I am guessing your domain filter will be something like this

[('create_date','>=','some date'),'|',('create_date','<=','some date')]