I wanted to do a similar thing with my PVR-350, but switching between tuner and SVideo input. What I did was kind of a hack, but it works for my purposes:
Added two menu options to the /usr/share/mythtv/tvmenu.xml file:
Code:
<button>
<type>TV</type>
<text>Select TV Input</text>
<action>EXEC /usr/local/bin/test_ioctl -p 4</action>
</button>
<button>
<type>DVD</type>
<text>Select DVD Input</text>
<action>EXEC /usr/local/bin/test_ioctl -p 6</action>
</button>
<type>TV</type>
<text>Select TV Input</text>
<action>EXEC /usr/local/bin/test_ioctl -p 4</action>
</button>
<button>
<type>DVD</type>
<text>Select DVD Input</text>
<action>EXEC /usr/local/bin/test_ioctl -p 6</action>
</button>
You may have to adjust the -p # to get the input you want. For SVideo it was between 5 and 7 so I just selected 'Watch TV' tried them all until I hit the one that that was displaying what I wanted. The composite inputs are 0-3 I believe. Again, this was a 350 so it may be different.
To use this, I just go down on the menu and select 'Select DVD Input', nothing will appear to happen, but then when you go to 'Watch TV' you will be watching the DVD input. When you're done, go down to 'Select TV input' and when you back to 'Watch TV', you'll be back on the tuner input. I'm not sure how this will interfere with scheduled recordings, or any other additional problems it may introduce, but it works for me
.