Wireless rear speakers? You want these in addition to some front speakers that don't seem to be there now? Your tv will likely let you use only the audio from the tv speakers or external speakers, not both so likely you're just looking at amplifying the main L/R channels of 2.0 sound (surrounds and rear surrounds in multi-channel setups don't even have full content so don't really help hearing dialog or other main speaker content). Likely the tv will only output audio over an optical connection (or HDMI/ARC) and you will need something to process the signal from there, so a regular audio visual receiver may do the trick, but such receivers don't have wireless speaker setups, they have wireless internet connections; they can use a wireless transmitter to active speakers (those that have built-in amplifiers, rather than passive speakers which requiire an external amplifier; I have two wireless active sub woofers for example).
Wireless speakers aren't really well established as yet, as the technology isn't the greatest quality wise across the whole frequency range plus there are still RF interference issues, but there are some kits from Rocketfish and Sonos you might check out (the Sonos likely can provide the processor for the optical output, don't think Rocketfish offers anything like that but not sure), at least I've seen wireless offerings from them.
I take it the problem may be in running wires from the tv to where you want the speaker?
Hopefully there's some tech I haven't noticed yet that someone else can point out that may work for ya! Good luck....
"I realize that somebody playing free music isn't as commercial as a hamburger stand. But is it because you can eat a hamburger and hold it in your hand and you can't do that with music? Is it too free to control?" - Don Van Vliet (aka Captain Beefheart) discussing commercial success in the music biz