“spDTSChangeOwner, available on the downloads page, is a convenient wrapper around sp_reassign_dtspackageowner. It accepts two parameters @old_owner and @new_owner, which should be self explanatory.”
As of this writing, download the script here:
http://www.sqldts.com/redir.aspx?1212
Sample usage:
EXEC dbo.spDTSChangeOwner 'Fred', 'John'
EXEC dbo.spDTSChangeOwner
@old_owner='MyDomain\\OldUser',
@new_owner='MyDomain\\OldUser'