Nothing to say here, just ebuilds for seafile as they aren't present in official repo.
To install seafile client you can run:
# emerge net-misc/seafile-client
There aslo some USE flags to configure building. This repo doesn't contain ebuilds for server version of Seafile because I don't have place to test them and also I prefer Docker for server side. Here you can find my Docker image for Seafile server.