Changing the directory where .pyc files are created

There's no way to change where the .pyc files go. Python 3.2 implements the __pycache__ scheme whereby all the .pyc files go into a directory named __pycache__. Python 3.2 alpha 1 is available now if you really need to keep your directories clean.

Until 3.2 is released, configure as many tools as you can to ignore the .pyc files.

This might be useful for some: Miscellaneous options, especially -B option:

If given, Python won’t try to write .pyc files on the import of source modules. See also PYTHONDONTWRITEBYTECODE.

Yes, starting from Python 3.8 you can control this behavior. The original discussion starts from pep 304 in 2003.

While this original PEP was withdrawn, a variant of this feature was eventually implemented for Python 3.8 in https://bugs.python.org/issue33499

In the result, you can control using PYTHONPYCACHEPREFIX=path, -X pycache_prefix=path and sys.pycache_prefix.