When you run a View Compare/Merge session, if the default action on a file is RE-PIN or MERGE, there is a new menu option called Skip a Revision.
If you select this item, you get a dialog box of all historical revisions of the file to pick from.
When you select a revision, View Compare/Merge attempts to temporarily remove that revision content from the source file, then use this output to regenerate a merge to the target file.