I'll suggest James A. Walker, former and final commander of the Stonewall Brigade before it was destroyed at the Battle of Spotsylvania as well as a Republican U.S. representative for Virginia. At the 1896 Republican National Convention, he received 24 ballots for the vice-presidency. Of course, that is less than 3% of the total number cast, so it appears that he wasn't that much a major candidate. Doing some more research, however, I found that his candidacy had mostly rode a wave of northern-southern reconciliation that the McKinley campaign was trying to promote, and that by the time of the convention, it had mostly exhausted itself, and certainly lacked the energy to push a former Confederate general onto the Republican ticket (although it should be noted that as part of his front-porch campaign, McKinley invited a large number of former Confederate soldiers from the Shenandoah Valley region to his home in Canton to take part in reconciliation festivities alongside Union veterans from Canton, and they did make some concerted efforts to swing the Upper South and Georgia into their camp.)
So, it is pretty doubtful if Walker could actually weasel his way onto the ticket. It would have to take an extraordinary amount of lucky breaks for the cause behind him for that to occur (although the general theme for the 1896 election seemed to be a series of lucky breaks for both the McKinley and Bryan campaigns leading up to their respective conventions.)