...digital optical switcher like this one @ Monoprice-
There's really no other way to do what you need w/o having to unplug cables, if everything is run through the receiver as it's intended w/ typical HT systems.
(Also, keep in mind ARC won't work since all your components don't support it.)
Here's how I would wire your system, but I am still not 100% satisfied that everything will work by merely adjusting/selecting inputs with the remote(s).
Skybox (HDMI out) --> (HDMI in) Sony HTIB
PS3 (HDMI out) --> (HDMI in) Sony
WDTV (HDMI out) --> (HDMI in) Sony
Sony HTIB (HDMI out) --> (HDMI in) Samsung HDTV
In addition to this, add the following digital optical connections & switcher to incorporate the wireless headphones to the mix, and allow at least partial audio (need to test it):
Skybox (digital optical out) --> (digital optical in) Monoprice switcher
PS3 (digital optical out) --> (digital optical in) Monoprice switcher
WDTV (digital optical out) --> (digital optical in) Monoprice switcher
Monoprice switcher (digital optical out) --> (digital optical in) Sony HTIB
My understanding is that the last connection allows you to listen to audio simultaneously from the X500 and your surround speakers. (Is this true 'pass through' to the Sony HTIB though?) Real world means you test this to verify, of course. Not sure how the WDTV streamer box will react while having both HDMI & digital optical connected at the same time. I haven't tried that yet with mine ;). Skybox rig & PS3 won't likely have issues with it AFAIK though.
Potential issues? Well, I am still not sure how that Sony HTIB will switch between different audio inputs connected to the same source input. I'm more accustomed to full fledged AV receivers in that regard.
Perhaps you would also need a second switch (A/B or on/off) between the monoprice switcher and the Sony receiver. IOW, to completely throttle any signal passing through so the HDMI portion isn't confused per se.
Let me know how it goes.