I did some preliminary research as well as visited the sites listed in this discussion. It seems that they have linked a Hard Drive Memory (HDM) to the system. Since memory is relatively cheap today it makes sense to store everything not on a disk but in memory (similar to the way the PSR2000 stores its information today).
I will try to get a translation tomorrow if I have time to see more about what they are doing. It is my guess that some aspect of the operating system must be changed or fooled into thinking there is that much space available to it.
I did find some replacement floppy information. There is the Imation Superdisk which holds 120 MB of info in a floppy sized disk. It is backwards comaptible and will read lower density floppies as well. They had an internal IDE drive that was 27 times faster than a floppy but they no longer manufacture it in the USA. I did not find any technical specification that said it could just be plugged into a floppy connection though it was probably designe as that. I found it priced from about $74-129. It operated under windows which leads me to believe that some modification to the 2000 might be necessary as well.
Since I just bought my 2000 back in August I am a bit concerned that opening up the Y2K would cancel my warranty. It still has that new car smell! I'm not even sure what kind of connection is used to drive the internal floppy on the Y2K.
There is also the CU-VFSD50 floppy disk adapter. This allows a user to use DS memory cards and insert them into a floppy disk looking device. Then the computer thinks it is looking at a floppy but it is actually a high capacity memory card. This might be enough to fool the Y2K by itself.
Obviously more research needs to be done.
Hope this helps a bit.

- Brian

Confused? Bewildered? .. Then my work here is done.