Cold backup restoration (if you willing to lose data after the backup) --

Restore all the datafiles, Control files, Redolog files (though you may not need the redo logs because with cold backup your database already may have applied all the transactions if there was no rollback at shutdown)

Then --
svrmgrl> startup mount
svrmgrl> alter database open

(this should open the database though you will lose data after the cold backup.

If you need the data after the backup (becasue you are in archive log mode) you should try the following method --

Assuming you have a copy of the latest control file (if you had multiplexed your control files and didn't delete all of them), use that Control file for Mounting the database (this control file has the latest SCN not the restored control file)

svrmgrl> startup mount
svrmgrl> alter database recover // this should automatically get the available archived logs and apply those.

svrmgrl> alter database open

Only problem may arise, if you don't have that copy of the control file then you will need the backup controlfile (if you had created one)

- Rajeev