I've installed a new 10 inch deep sink (single bowl) in my kitchen. Now the garbage disposal output sits about 2 1/2 inches lower then the drain pipe.
What is the best way to run the drain line from the disposal to the slightly higher house line?

I ran into the same problem for the same reason. I never did find and easy solution since water doesn't like to run up hill. I had to go through the fllor of the cabinet and into the basement where I was able to T into the existing drain. It was all PVC so the cuting wasn't too bad but it was not fun. Do you know if the drain inside the wall runs down or horizontally for a few feet. If it runs staright down you may be able to open the wall and add a T to the existing drain.