There IS no central seed-server.
But there are GWebCaches, a disributed seed-serrver-network (if I may call it so).
Check
http://gnufu.net for some user-friendly information on Gnutella. You will find a link to the rfc for devs there.
You can simply fire up a client on a computer in your network and let your client try to connect to it.
Please don't connect to the general network, before you test it on a local machine, this could only give you a bad reputation amongst the other developers, if your client should be faulty.
You might want to try phex (
http://phex.kouk.de) to check against.
It is very customizable and might fit your needs.