fatblokefletch wrote:
Firestick has an app which you can control via to a mouse through the mobile, so the interface would not be a problem.
I have sideloaded Now TV onto the firestick and it works ok
well it costs nothing to try a sideload and test, see if you get as far as a "register this device" screen. I am still skeptical though - its hard enough getting TVA to work on approved devices even 
it will cost you one of your precious one-per-month device activations to continue & remember there's a two device global limit also for TVA in your account
the real show stopper will be the built in block that dis-allows the app from displaying on any external screen., it's going to class the HDMI out from fire stick to TV as an external device, and block it, just like it would a HDMi cable running from an otherwise approved HDMi capable tablet into your TV.
there are some older threads on this board saying that e.g.
"as the licencing prevents TV Anywhere on mobile devices from outputting to a TV then there would be little point making a app for the fire stick as it has no build in screen so wouldn't be allowed to work under the rules the channels have set"
http://community.virginmedia.com/t5/TV-on-the-go/Is-Virgin-TV-Anywhere-going-to-be-on-Amazons-Fire-TV-stick/td-p/2834182
FYI if I go to my apps and devices at amazon, I see my copy of TVA ( which works on my FIre HDX tablet) but am told it is not compatible with my Fire TV / Fire TV stick.
IF you choose to press on & see for yourself: ( & please post results if you do )
how I'd sideload it: From an android tablet install an app backup/restore utility , then copy the TVA .apk to a PC shared folder via es explorer, then copy from there over LAN to the stick via es explorer on stick. l [ or if you are starting with a google tablet, there's something called APPS2FIRE in the pay store which I have never tried)
Launching sideloaded apps on the stick is a pain though as they will not show on main menus, unless you install more workaround stuff to patch that issue.