Since the WISE satellite operates in the infrared, and has proven useful for
disproving the existence of planets closer (relatively speaking) to the Sun:

http://www.gizmag.com/nasa-wise-planetx/31148/

Wouldn't the James Webb Space Telescope (which also operates in the infrared)
be able to spot planets even farther out?

If not the JWST, what would be the best type of astronomical instrument for
spotting objects like the ones mentioned in the article cited in the OP
(something build-able with today's technology)?