If you want the cutting-edge version of ChipWhisperer, you can clone the repository. If you have Git already set up, this is easy to do:
git clone git@github.com:newaetech/chipwhisperer.git
cd chipwhisperer/software
python setup.py develop
You may also want the OpenADC software, which is necessary to build new firmware for the ChipWhisperer FPGA. This is unnecessary for most users. If you need it:
cd ..
git clone git://git.assembla.com/openadc.git
cd openadc/controlsw/python
python setup.py develop