need vertical split on range browser

I can’t find a way to make the range browser (as described in http://www.gregsexton.org/2011/05/gitv-range/) do a vert split.

I have a terminal that is much wider than it is tall, and some of the functions I wanted to really test/play with this feature on require as much vert space as possible.

I realise a horizontal split is better if you anticipate opening up a diff view on that file later, so that is certainly a good default but it would be nice to be able to override that.

Thanks...