As that site suggests I dump the pulp and seeds in water. I'm small scale so all this is done in a clear drinking glass or measuring cup.
After a few days the pulp will begin to separate and float, seeds sink. Break up large clumps if needed. Every few days I pour in water, overflowing the container and flushing out the pulp till just seeds remain. Then put the seeds on paper to dry.
This works for many types of seed.