Trying to get kernel version a couple revs back

I checked mailing list archives and faqs and couldn't find a yes or no for
the following. What I would like to do is checkout a version of the ppc
linux kernel a couple 'kernel versions' back. Specifically:

2.4.20-pre8-xfs

or

VERSION=2
PATCHLEVEL=4
SUBLEVEL=20
EXTRAVERSION=-pre8-xfs

Is there a (combination of) bitkeeper command(s) that will let me do this.
In fact, it doesn't have to be bitkeeper ... just a means to get this kernel
version.

Thanks,

-- Brian

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