Well I assume you read the 1st post, also known as instructions?
Make sure "virtual memory" is off in the control panel.
Make sure to save the deb to flash while installing, not on the SD card your trying to destroy.
Finally if you still can't install, POST you error log here
Hi! I spent several hours flashing and reflashing my N800, trying to find a way to boot from internal mmc card. I did try both ways: the "step by step" method, from this topic and the .deb file, made by mr penguinbait. The result was similar - proces was uncorrupted, boot menu is functioning properly, but after choosing "boot from Internal MMC card, partition 2, ext2" the screen gets white, with information about booting above. After then Nokia appers to attempt to boot from mmc: during several seconds and sudenly reboots, goes back to the boot menu, or shows message: Result is similar. I have no idea what to do next. Is there any other solution? Many thanks, for any clue. Vect0r.