I've released PowerPacker RC12 with support for USB thumb drives. Thanks to Ilko for allowing reuse of his code.
I've adapted it to support compact packing, as described in the changelog here:
1. Added the capacity to pack files to usb thumb drive and hard drive using code from WinSetupFromUSB. Thanks go to Ilko for permission to reuse his code.
2. Added the capacity to pack installations in the same directory. This compact packing means that if a file is already present in the powerpacker destination directory, there will only be one copy of it. For example, let's say you are packing XP Pro Corporate, Retail and OEM edition. In reality, almost all the files from these editions are identical. Compact packing takes advantage of this fact by putting all the files in the same directory, except the ones that are different. The different files are relocated elsewhere and txtsetup.sif is adjusted accordingly. This feature works for ISO Packing and USB Packing. This feature is the most interesting for USB Packing since it means you can pack more installations onto your thumb drive.
3. Added Tablet version among the possibilities of the Xp version. The menus are created accordingly.
The principle is from here as explained by Siginet. I've automated the process.
I suggest that you pack all your editions of XP Pro together. Then, in another directory, pack all your home editions. Then, in another directory, your MCE OEM editions. My attempts to pack together MCE OEM and VLK were not successfull. Finally, I suggest you pack all your tablet editions together in a fourth directory. Then, repeat the process for other languages. In other words, you should have 4*NumberLanguages different packing destinations.
I have tried packing Home and Pro editions together, and managed to differentiate the only file that is different in the boot directory, setupreg.hiv, but upon entering into GUI mode, the installation gives an error message. That is why I suggest packing them in different directories.
I've removed WinSetupFromUSB's code that checks if there is enough space left on the destination drive, as compact packing needs so little space. I suggest, however, that you keep about 1.5Gig free at one time on the usb drive since Driverpack integration is done directly on the usb drive. For instance, let's say you pack together pro vlk, oem, retail. Then you pack home oem, retail. Then you pack tablet oem, vlk, retail... Move the first directory containing pro onto your internal hard drive, and when the pack is done for tablet, move the pro directories back. You may not have to do this, it is just a suggestion.
WinSetupFromUSB packs files into the temporary directories used when windows is installed from dos. The newer beta versions of WinSetupFromUSB use another strategy, but the code is not yet released, so I used the available code. When you pack another windows installation onto your thumb drive using WinSetupFromUSB, it renames the directories for you. I do that right away with Powerpacker, and have tweaked the GRUB menu system a bit so it looks mostly like PowerPacker iso generated files' interface.
Also, sometimes, windows setup erases the setup files from the usb drive. The way the generation works, is that a file named migrate.inf is created whose role is to make the usb drive read only so that windows does not erase the setup files from it. Sometimes, the migrate.inf generated does not work. I'm not sure why. To work around that, I suggest you back up the contents of your usb drive to your internal drive before installing windows. Then, if the installation is not deleted, make sure your migrate.inf files are all the same in your other installation directories. That way you should be safe.
Lastly, to test your USB thumb drive installations, you may want to test it on your machine, or on a virtual machine. I find that VMWare's USB 2.0 support works well with my thumb drive. Use plpbt.iso to add the ability to boot from a usb drive and voila, you can test your usb installation at usb 2.0 speeds! Or burn the iso file to add the ability for your computer to boot from a usb thumb drive. Why do that? Simply to test the thumb drive before you use it on your netbook which does not have a cdrom drive and which does support usb booting.
Feedback is appreciated; let me know if you find any bugs.