As a student, ask around or check with your advisor. Most labs will have positions for students interested in coding "grunt work" because students are cheap.

As a professional, apply to Masters/PhD programs in your area of interest, or be young and an expert in an obscure technology the lab uses. Some labs will hire out contract work, but can't pay well (hence be young). Other labs have grant money to bring in non-phd researchers, but to get the job you'll both have to be an expert in a required technology, and be able to contribute actively to the research area of the lab. At Yale, I did this, as second author on a conference paper showing novel methods for applying machine learning in multi-agent, sensor -driven environments. It justified my paycheck as a researcher while I spent the other half of my time fixing broken code for other researchers and writing the first version of the software for our lab spinout.

Edit: I just want to clarify that my experiences with this don't go past 2010, so YMMV. Getting old is tough sometimes, it still feels like almost yesterday.