How to use a rest service result as valuelist for a value picker control

How to use a rest service result as valuelist for a value picker control

An external Domino Server exposes application data, which I need in my
application, as a Rest Service. In fact, they use a viewJsonService and I
know they exposes column1 up to column8, but I have no other access to the
data. The URL looks like:
http:\extserver\database.nsf\restservice.xsp\extdata, where 'extdata' is
the pathinfo.
I want to consume the data returned by that Rest Service as an input to
the valuelist of a value picker control in my xpage. In detail, I want to
use the value from column2 as the value in the value picker and the value
from column5 as the label in the value picker.
Any idea how to do this ?