Well the tutorial on my site is designed around the SSD version (DFI files etc.) but you can relatively easily adapt some of the stuff to the other versions.
For example, the HDD version also uses SQX files so you will need to get the squashfs-tools that I list on my tutorial, but you won't need to create an updated DFI file or use the patcher to update it. You can just grab the SQX files directly off the SplashTop partition, modify them and re-compress them before putting them back on the correct partition.
Just keep in mind that if you do modify any system files you will need to update the version file, just download the DVM-Version.exe file from my website and run it in linux using the following command:
Version number is formatted like this: x.x.x.x
mono DVM-Version.exe [Path to SplashTop directory] [Path to new version file] [Version number]
Good luck, and I'm sure you will be able to find any other information you need in the forums