Simple `to_tsvector` configuration - postgres
You would have to code a custom parser. This can only be done in C.
But you might be able to use the existing testing parser test_parser, it seems to do what you want. If not, it would at least be a good starting point.
The problem may be that this is in src/test/modules/, and I don't think it ships with most installation packaging. So it might take some effort to get it to install. It would depend on your OS, version, and package manager.