Yes the location annotations tie the expressions back to the original source - see the examples below.  Note there are also symbol annotations.

I have implemented the following:
-fgenerateIR - output the IR of the graph to stdout after the graph has been normalized (i.e. ready for processing)
-fgenerateIRAfterTransform - output the IR after various transforms have been applied
-firoptions=<n> - override a few details of the IR output. Values are ored together. 1 means inline simpletypes. 2 means inline atributes.

Here is a sample temp.ecl:

This is the output of before transform:

Here is a version after transformations, but keeping simple types inline (options default to 1):

There are various other places the IR could be generated, and It might be possible to generalise the code to configure that if it proved useful in the future. This should be enough to be getting on with though!

If the emitted IR could include pointers back to source code (attribute file/line/pos) that would be extremely helpful as well.

EDIT: Is that the "{location '',1,1}" (as an example) information in the existing IR? If so, great!