Since you managed to screw things up such that it won't boot, use BackupMenu to make a backup(preferably to a MicroSD card) of your rootfs and optfs. Then, go reflash, restore etc. Once you have a working system(but, obviously missing your contacts/sms), you can pull those files out of the backup image you made(I forget the exact file, but someone will know) and then someone can guide you through sticking that new copy back in place.

You shouldn't have to do the slipstreaming thing; the contacts file isn't critical to booting, so you can just modify it/move it from xterm while the device is running.