okay. here's one that worked for me on 3. (3.3, SDK 1.2, Java 1.4.2_19)
(remember to derive from com.amazon.kindle.kindlet.AbstractKindlet
as shown in this project...)
Included the sign.sh that you call like ./sign.sh filename.jar
Included the developer.keystore from ixtabs font project.
you run it against the EXPORTED jar
dump the final azw2 in /mnt/us/documents
should be golden.
dbus-send --system /default com.lab126.powerd.resuming int32:1
is an optional file you *could* make, to assist in quick index updating (that's what I run).
hope this helps someone like me who was struggling with the info that is mainly for 4 and 5's these days.