As we mentioned in our ticket, if you do not prefer to spend $90 on mailing the Yubikey which could be lost, you can always order a new Yubikey from our page https://yubikey.mtgox.com/ for less than $30.

Regarding giving you limited access to your account; we have been asking you on the Support page several times whether if this is how you would like to proceed. If that is all right, please let us know on your ticket and we can resolve this for you.