Mercurial 3-way Diff without merging

I have WinMerge configured to compare two arbitrary changes:

hg windiff -r 23 -r 37

I have kdiff3 to be used for 3-way comparisons during merge resolution.

How to set up mercurial to use kdiff3 to compare 3 arbitrary revisions like:

hg 3diff -r 23 -r 36 -r 37

I would like to be able to get information on things before starting a merge or reload.

(Is it possible?)