How to restore a deleted HFS+ partition table?
Since the table has most likely been written over, scanning for the files and backing them up that way is probably the only option. DataRescue is one of the more popular ones.
Don't write any more data to that filesystem or drive. You might try if DiskWarrior can scavenge some of the HFS filesystem metadata, but a program like Data Rescue is your best bet for recovering all of the files that are still intact without needing any filesystem metadata.