XCode Tools

Hello, I'm trying to install the xcode tools in instadmg. Has anyone had luck with this? The main installer package is a small 40k installer, that points to lots of other big packages. I have the .dmg for xcode, and tried just putting that in the custom install folder. Nothing was installed on my image. The logs don't show anything. I'm using 10_5rc1 of instadmg. I read a previous post, talking about using instaup2date to do this. I couldn't really get my head around instaup2date enough to get this working. Has anyone got tips to get this working without instaup2date, or be willing to help me get instaup2date working enough to install the dev tools? Many thanks.