After reading this tread
New life for H120 DAP's ! I ordered the CF-adapter at
LinITX.com - Compact Flash to 1.8" Toshiba HDD Adapter
The adapter arrived yesterday and I used the instructions on
CFModGuide < Main < TWiki to install the adapter. I am using a Sandisk II Ultra 2.0 GB for testing and amazingly it works!!
However, sometimes I have difficulty reaching my folders and I am not able to initialize the database. But besides that it works very stable! It is running now for 5 hours without any crash. I will continue testing!
Update: I made a patched build specifically for CF modded devices (see also
FS#8644: Make Rockbox work with CF modded devices). It seems to have no problems anymore with freezing of folders and I can use the database again.