Vandersteen 2Wq corner placement?

I think it will be kinda tough to get a single sub in the corner to integrate properly. The only way to know is try it. No two rooms are alike. It really needs to be between the speakers on the same plain. I think you will get a little bit of directionality(you will be able to hear where the sub is located.)
The 2wq has lots of adjustment possibilities. It is always possible to get a combination that will work.
I use a pair of the 2wq's(one in each corner)It is an excellent sub for music. It is very tight, quick and dynamic. A lot of people are on the REL bandwagon. In direct comparison, the Vandersteen is a better performing sub in my system. There are some very good design reasons for that. The idea here is not to "Hear" the sub but just give you the lower octaves of music when called for. The Vandersteen does this extremely well. It is also extremely well built. I personally think it is a lot better buy(as in more for the money) than many other subs.
With that said, the REL offers some unique adjustments that may help you in your particular situation. Paradigm also makes a couple of excellent subs and some others as well. You will really need to experiment to find what, if anything, really works.

The corner behind the speakers is the best place for your sub.

I also have a pair of 2Wq matched to MG 3.6R. One of the subs is in a corner directly behind a speaker. The subs are properly intergrated and cannot be localized. I also have a V2W that is placed in the back of the room for HT.