I can find the C++ source code for MOPSO without much difficulty, and with more work I can find some papers whose summaries hint that someone has implemented it in MATLAB.
However, the only possible implementation in MATLAB that I can seem to find is here. The summary of it on that page makes no sense at all, and the code was only uploaded a month ago. I would exercise caution with regards to that source: it might be perfectly fine or it might be booby-trapped.
