Availability
QSOPT is freely distributed with source (and pre-compiled libraries) from http://www.isye.gatech.edu/~wcook/qsopt/.
To use the solver in YALMIP and MATLAB, a mex interface is required. Pre-compiled mex-files are available at http://control.ee.ethz.ch/~johanl/mexqsopt.php.
YALMIP
QSOPT is invoked with sdpsettings('solver','qsopt').