restore data from DB base?

One server that hold postgresql(7.4.6) and data(account system data) stop working yesterday, the disks may be demaged. the data wasn't backuped.  Does anybody know how to restore data from DB base. That means, if the data directory could be found from disk, is it possiple to install  a postgresql(7.4.6) in a new machine, copy data directory to new machine, then try to restore data ? But how to ask postgresql knew the data directory?  Any suggestion will very be apperciate.

Thanks