You may not be able to get there from here, sorry to say.
The audio is output from the bluRay player as either a signal on the HDMI cable, or it can be output on the coaxial port as a digital audio stream. Your receiver has a single digital audio input, which appears to be in use. Unfortunately, government regulations forced manufacturers to remove analog connections on blu ray players last year due to copyright fears.
You can make this work, but it is going to take purchasing another piece of equipment or two.
First, you can convert the coaxial signal to optical with this:
http://www.monoprice.com/products/p...=10423&cs_id=1042302&p_id=2947&seq=1&format=2
Then you can use a TOSLINK switch to get multiple ptical signals into your receiver:
http://www.amazon.com/dp/B003C15798/?tag=satell01-20
However, note that this will end up costing around $75 and will be a bodge type solution. This may be the time to update to a more modern receiver. You can purchase a modern receiver for around $200 which would allow you to do all your switching through the receiver over HDMI. It would simplify your cabling and give you better audio to boot.
Some suggestions:
http://www.amazon.com/dp/B007R8U5VM/?tag=satell01-20
http://www.amazon.com/dp/B004O0TRCO/?tag=satell01-20
http://www.amazon.com/dp/B004QQXDVC/?tag=satell01-20