Honestly, I'm not a connections expert at all, but it looks as if you could use either the digital audio output or the optical out from your PS3. I have read that the Vizio has both inputs, but don't take my word as gospel.
Why don't you give Vizio a call, and choose the option for tech support? It will be faster, and more authoritative than our exchanges. My only concern...and this is something you could ask them...is whether the 42 inch bar will give a wide enough soundstage for your 65 inch TV.
To make it easy for you, here is Vizio's telephone number:
Toll-Free: 888 VIZIO CE / 888-849-4623.
No ETA on the 54 inch model, which also, as in the case of the 42 inch model, will have the satellites tethered to the wireless sub.
Please go to the Soundbar Forum to the "Vizio's New True 5.1 Soundbar S4251W" thread, and check out posts #67 and #68. The poster is connecting his PS3 via Optical, and achieving 5.1. Also, all that is required to lengthen the wires to the Satellites is an RCA coupler and additional RCA cable from RadioShack.
But you should still call Vizio, particularly as it pertains to the size of your panel.