Dear Arturo,
Your question is too old. May be you have already found the way to do what you want.
If my understanding is correct, we had a similar issue.
Consumptions from consignment stock are made at standard price by default. AKO transaction is not taken into account by Material Ledger and it causes that differences among std price and consignment liabilities are not considered, which causes reconciliation problems.
There is a modification available by SAP Note 988658: AKO posting for consumption from vendor consignment that works well, enabling the consumption liability (price from info record) to be used for consumption posting.
Hope it will help.
Best regards,
Flaviano.