tar them up, transfer, untar them preserves times.
The general problem is that to preserve things, you need to be enabled and ftp (as a client) is not enabled (setuid).
If you can use scp, I believe that preserves times.
Lastly, I have written "retouch" scripts where you record the ownership/times in a flat file then restore them by running a "restore" script. This must be root enabled to restore, however.
gene