The RGLoader team just pushed out a update of their devkit nandbuilder for RGH/Jtag console =).This new bring the support of lastest slim motherboard revision (corona) and also add some nice feature like custom bootanim.

You can also read the full features and explanation of the project by the RGL Team here

You can find some custom bootanim on Spiffy360

A tutorial is availiable HERE

Full Changelog

0v300
-Xshell start button redirection
-Retail profile encryption support (thanks Dwack!)
-RGLoader.xex
-binary patch loader
-Added system extended partitions to xbox neighborhood
-Xbox live signin notice toggling
-Added corona support
-Updated to 15574 kernel
-Added minimal mode indicator on screen
-Fixed slim/rgh minimal mode
-Added custom boot animations
-Fixed dash extended package crashing problem

This version is currently compatible with

Motherboard
-Xenon Jtag 16MB
-Zephyr Jtag/RGH2 16MB
-Falcon Jtag/RGH2 16MB
-Jasper Jtag/RGH2 16MB
-Trinity RGH 16MB
-Corona RGH 16MB

*** This version does not have RGH 1 support it is W.I.P and will be done in 12 days when tydye returns ***

Instructions

You will need .NET Framework 4.0 or 4.5 installed. May also work with Mono.
-Copy rgloader.ini and bootanim.wmv to the root of the hard drive.
-Copy the contents of hdd-filesystems to ‘Hdd:\Filesystems\15574-dev’
-Extract the 0v300 builder rar to a folder.
-Copy ‘filesystems’ and ‘loaders’ to the 0v300 builder folder overwriting files/folders.
-Run the launcher and build your nand
-Open the RGBuild Launcher and type in your CPU_Key and select your build options.
-Click the NAND button to browse for your source nand image.
-Click “RGBuilder” button to start the process.
-Output will be next to this file named: Image._____.bin
-Flash this with whatever flash tool you wish.