I'd say contact the CPAN people and explain the problem, stating the fact that you have a working module that is a good replacement. Switching maintainers happens when there is no way to contact the author.

Otherwise, as much as I dislike duplicated code, I'd go for the option of taking the code from Sys::HostIP and putting it into your own module directly. It happens all the time, and is a better solution for end-users than having to use two different modules while you wait for ownership transmission to happen. Plus, it's likely that over time you will come up with some changes to that part of the code, and a year down the line it might not even look anything like what you ripped^W^W^W^Wborrowed from HostIP.

PS: have you tried a google search on the author's name ? It often yields some info...