Create portable user via a script/command line?

Hello Everyone, I am going to be doing a fairly large user migration from old iBooks with 10.4 to new Macbooks with 10.5 and portable accounts this summer and I'm trying to automate the process as much as possible. I currently have everything 90% complete; ASR, Package Based Image, post process scripts to transfer user files & verify that everything went according to plans, ect... The only problem that I couldn't sort out is the creation of mobile accounts via a script/command line. I know that mobile accounts are stored locally, and I just can't seem to find the required differences between local and mobile accounts in order to create them via the command line. If anyone has any input I would truly appreciate it. TIA