There is a file for the DAVS 300 that looks like it will work:
[Link: remotecentral.com]It is listed under DVD. The codes in that file are are for multiple devices DVD, Receiver, Tuner etc. and that is what you will need to fully control your unit.
Obviously elmbeck you wll need a translation utility for the NEO.
There is an excellent site for Sony codes but they are in true device and command and you will have to use MakeHex or some other Pronto hex generator to create the commands.
This is the section for your units. Most of these commands are in the file above. If something is missing from the first file let me know and I can tell you how to create the commands with MakeHex.
[Link: anycities.com]-Jon