Okay, this is probably easy, but I don’t know proper words to describe it, and hence, google it…
I have an external script which takes a file name and outputs this:
/path/to/file.py:683:80: E501 line too long (85 characters)
/path/to/file.py:690:21: other error message
..etc..
Now, I know this output format is widely accepted by other, much simple IDEs, e.g. EditPlus. I don’t know how to integrate it with Eclipse though.
I want this script integrated with my editor windows. I want Eclipse to run it in the background, every time I save the file, and then parse the results and mark all the lines which occured in the script’s output. It should look something like this:

How can I do that?
Note (for those who know why I need this): I know PyDev has a pep8.py checker integrated, but it’s not enough.
Ok, so I implemented that plugin myself. I does exactly what I asked for, I guess. I made it configurable with some rude regular expressions.
I posted the code and installation instructions here (GitHub).