Best way to harvest Crassula seeds?

[Amie]

I have a ton of dried flowers from some different Crassulas, and I'm wondering what the best way is to harvest seeds. Right now I have some dried flowers in a bowl, and if I crunch the flowers I get what I think is tiny seeds, in addition to a lot of dried flower and stem bits. What is the best way to separate the seeds out? And, is there any special treatment the seeds would need before planting them? (Cold treatment, etc)

I'm also curious to know if Crassulas have self-fertile flowers or if they need pollination from another plant.