You cannot eliminate counterparty risk from an asset-backed currency peg, as there is no mechanism at the protocol level to stop the issuer (i.e. the user with the private key of the address with the XCP backing) from withdrawing funds. I still think though that is a really good use-case.

A currency peg that actually requires no trust is making a CFD on the price of an asset to which you would like to peg your holdings in XCP. The effectiveness of the peg, however, depends on one's leverage, which in turn increases one's risk. For anyone who is interested in making such a peg, I have come up with a few examples which would show how you do it.