Look on the mtgox website, the bankruptcy trustee took control of it and posts updates there. He says he's informing creditors who filed by the Offline Method of the results of the acceptance or rejection by sending emails.
If you had an email from him, then you could try informing him of your change of address through an emailed reply.
https://www.mtgox.com/
Bankrupt Entity: MtGox Co., Ltd.
Bankruptcy Trustee: Nobuaki Kobayashi, Attorney-at-law
The bankruptcy trustee says nearer the time of distribution he will allow those who applied online to change the addresses in their bankruptcy claims. Try asking him through email how those who applied offline can do the same, and when.
However, nearer the time of distribution, the bankruptcy trustee is planning to give Users an opportunity to use the system again to make changes to the details of their bankruptcy claims, other than increasing the amount of the bankruptcy claims that Users have filed (for example, changes in their addresses or company names).