Net::FTP doesn't support chmod... but you can use quot
from the Net::FTP POD:

quot (CMD [,ARGS])
           Send a command, that Net::FTP does not directly
           support, to the remote server and wait for a response.
[download]

Update:Also check FTP manpages compared to the RFC 959

Greetz
Beatnik
... Quidquid perl dictum sit, altum viditur.