This Consulate is unable to issue powers of attorney executed by foreign nationals, who can instead sign the document in front of a Notary Public (see link Patronati for a list of Notary Public services) and legalize it for international use through Apostille (follow the link for an explanation of the procedure).
If the original document is written in English, the interested party is responsible for having it translated into Italian, and for subsequently getting it apostilled as well, through the same procedure. The apostilled original and translation should be submitted concurrently to any Italian recipient.