imposm.parser runs with Python 2.5, 2.6 and 2.7 and is tested on Linux and Mac OS X.
The PBF parser is written as a C extension and you need to have a C/C++ compiler, the Python libraries and Google Protobuf.
On Ubuntu:
sudo aptitude install build-essential python-devel protobuf-compiler libprotobuf-dev
You can install imposm.parser with pip or easy_install.
pip install imposm.parser
easy_install imposm.parser