I suppose you can use ReferenceStream in the following manner:
(this code fragment is from Mark Guzdial's PluggableWebServer)

saveTo: filename
	|f|
	f := ReferenceStream fileNamed: filename.
	f nextPut: self map.
	" can put your own object instead of (self map) "
	f close.



restoreFrom: filename
	f := ReferenceStream fileNamed: filename.
	self map: f next.
	" (f next) reads the next object "
	f close.

ReferenceStream handles objects that contain objects, etc., and even 
handles loops.

--
Bolot Kerimbaev
http://bolotiq.freenet.kg/