Supertranslations, a simple example(?)

Now that the mystery is unfolding, I'm trying to catch up
with the new concepts. Especially the supertranslations. In
http://arxiv.org/abs/1603.07706v1 [1] they are said to be
at Null Infinity. Elsewhere I get the impression they must
affect the event horizon of a black hole. So I wonder: is
it possible to give an example of a supertranslation?

Is it possible to indicate where exactly it takes place in
the Penrose diagram of the transient black hole like this:

z|\
z| \
z| \I+
z| \
z| \
z| \
h/ /
h/ /
h/ /
h/ /
z| /
z| /
z| /I-
z| /
z| /
z|/

(Better picture at http://i.stack.imgur.com/Qtjrx.png [2])

Are the (relevant) supertranslations:
1) Everywhere in space, or mainly near the horizon "h"
2) Are they movements in the Penrose diagrom plane, or
in the orthogonal 2-sphere directions, or a mix?
3) What do they transform? The coordinates, the scale
factor, the locally attached sphere radius, or all
of them?

Just one example would be nice. (Or maybe I overlooked
it in [1]?)

[1] Kapec, Raclariu and Strominger
http://arxiv.org/abs/1603.07706v1.
[2] Copied from a different discussion in

http://physics.stackexchange.com/questions/22498/from-where-in-space-time-does-hawking-radiation-originate

--
Jos