I don't know why it's missing from those files--or why those files are
posted there in the first place, and how exactly they relate to my
stuff--but here is what it should do:

--------
accumulatePairsForBecomeIn: aBlock
	"Code in aBlock will add pairs to the argument, which is an OrderedCollection.
	When the block has been evaluated, all pairs will have their elements becomed.
	NOTE:  Do not use this method unless you understand about become."
	| mutations pairs |
	mutations _ self new.
	aBlock value: mutations.
	mutations isEmpty ifTrue: [^ self].
	pairs _ mutations asArray.
	Smalltalk isSqueak
		ifTrue: [(pairs collect: [:p | p first])
					elementsExchangeIdentityWith: (pairs collect: [:p | p second])]
		ifFalse: [pairs
					do: [:p | p first become: p second]]
--------

The reason it's this way is because my design requires that some of
the loaded objects become different things after loading. Individual
become: is fast in VisualWorks, but in Squeak bulk become
(elementsExchangeIdentityWith:) is the only way to get acceptable
performance.

Cheers,

--Vassili