I have a similar setup to this, however, I am fortunate to be in the US, and have schedulesdirect.com for my dish network program guide data. During the initial setup, Sarah should have seen your pvr500, I have 2 pvr150's which is very similar to a single pvr500.
During the setup of the Media Player, my dish dvr was not a member of the list, so I had to use webadmin and create this device, after that was done, It was seen by Sarah. The first instance of my pvr150 was for the "Live TV DVR522" shortcut on the LMCE menu. Then the second instance was for the MythTV part of the setup, where I had to enter my schedules direct information. This part you will not be able to complete, as LMCE uses schedulesdirect. As you have Sky TV, you will need to run mythtv-setup manually.
You can do this by using the "Computing" > "MythTV Setup" option within LMCE, or by going to a KDE Desktop session, and using konsole (terminal) as user root to run 'mythtv-setup'
Once this is done, and you have run mythfilldatabase, you should be able to access the sky box, via the "TV" shortcut on the LMCE menu.
However, without the need of the USB-UIRT, although you will need this for recording TV" By selecting "Sky" or "Live TV Sky" from LMCE menu, you should be able to use your existing remote, and watch TV through LMCE. This you should be able to do now, provided you selected the right input during the Setup Wizard.
I am using 2 Dish Network Receivers, and they work both in MythTV, as well as "Live TV"
If there are any other questions, please post them, I will try to help as best I can.