| Try and find a guitar-shaped, tight box, obviously not a refridgerator one. Cardboard boxes that basses come in work well, ask around at guitar shops for old ones. Then just logically surround it with foam, bubble wrap, etc. Make sure to have an UBER high amount of support under the head/neck, so it doesnt snap. I'm not too sure as far as loosening the strings or not goes, hopefully someone else can help. then tape it all up and secure it.
Hope this is of some help...
Adam | 
