biggest problem for me is, that the /flash partition and also sdcard uses fat-format as default. That causes problems with the linux file permissions, fat does not support them. Has anyone tried to insert a ext3-formated sdcard? It would speed up testing if the 7HT mounts it. ATM i have no spare micro-sd.
Another way could be compiling loop-support for kernel and mount an ext3-image-file from sdcard or internal memory. That way we dont need to change any partition type. But i am not sure about loop-support. Does this work as a module?
There is support for up to 8 loop devices, they do work already at least for mounting. As I understand it busybox has a bug when un mounting loop devices, but it could also be an implementation bug in the kernel, there is a bug regardless, loop0 stays listed in ps and you get errors trying to mount another image using loop. I have had some luck remounting a partition using loop. I'd recommend using the sdcard for storing fs images, the internal memory is kinda FUBAR, reminds me of those 8GB mp3 players you see on Ebay.
If you want to try other busybox files, there are several over a busybox.org for arm, different versions, best to compile the latest against the Archos toolchain. I'll take a look at it sometime myself, just have to create a compile environment.
User fun over at slatedroid had a combo boot/system ext3 partition on his sdcard working, all you do is modify the parameter file to point it at the sdcard device (mmc..0p1) instead of the mtd boot partition.
BTW, you don't use fdisk with the tablet, there are no partitions like in hard disk partitions, more like dividers defined on the command line to the kernel. Only point in using fdisk is on the sdcard itself, and best done in a card reader on a PC, not from the tablet.