The original idea of using VB.NET to do this was mainly just to change the startup application and upload a few splash screen images. This seemed quite reasonable with a bit of VB.NET wizardry. Creating a fully customized package has since come up as a better option, so I will be reading through that link in great detail, thanks for that! I didn't bother googling it because I knew it was based on Linux and from conversations I'd had with Maemo developers it was going to be a tough ask to block other functionality on the device. Now I know better.