For debugging you do not want to use the .hex, you want to use the .elf, the .hex does not have all of the debug information in it. The .elf contains both the .hex and debug information. This is outlined in the document.
Good luck, let me know how it goes.
I'm using the latest version of MPLAB downloaded off the Microchip web site - 8.76. I'm also using the Blink program as the test - I can change the delay times and re-compile to give an easily identifiable new program from the LEDs operation on the board - just to make sure I am actually uploading a new program.
MPLAB runs up and recognises the PicKit3. I also can import the .elf file and debug/program it into the Uno. I also load the .pde file but I cannot get it to set breakpoints. When I double click on a line to set a breakpoint, I only get a hollow red ring in the left hand margin and when I debug/run, I get an error message saying
"One or more breakpoints could not be resolved...Select breakpoints from the debugger menu for details"
When I select the breakpoint menu, no breakpoints are shown.
If I get rid of the message, the program runs. If I halt it, a debug window appears showing the program stopped at a line (usually in one of the delay loops in Blink). If I try to Step Through or over, the whole lot appears to hang and I can only get control back by doing a Debug/reset.
The only way I can get the filled red ring with the white B to appear on the left hand margin is to set my selected tool to "None".
Also, the bootloader I reload onto the Chipkit only seems to let me compile sketches, but doesn't run them. This bootloader is downloaded from the Digilent site and is dated 19th August.
So good in parts - and I'm stuck with a Chipkit which will only run under PicKit3 control with no debugging.
All good fun.
PS - What a miserable forum - only allows up to two smilies.