Thanks to the incredible work here, I have upgraded two of my old 8gb Creative Zens to rockbox and am beyond happy with the results (database covers both the internal memory and the SD card - I have 32gb on both - and all the songs are found & very important for me, I can change the left/right sound balance!) Since I had to dig around to put the procedure together, I thought I would reproduce exactly what I did to get mine working. I am using Windows 7 64 bit, but I expect the procedure should be similar for other windows versions.
01. Download the following firmware files and store them in an easy location on your computer hard drive (you can scan earlier forum posts to understand history of these) https://www.dropbox.com/s/nlgm4857t0d8btr/firmware-zen-beta.nk https://www.dropbox.com/s/9vwc4qdyh0c6e0p/sendfirm.exe https://www.dropbox.com/s/t96injmo9d2jhgt/MTP_DLL.dll
02. If needed, disconnect your Zen from the computer
03. Shut off Zen by pressing reset button (with paperclip inserted into hole bottom of unit) - you can't just toggle the on/off button
04. Start up by holding the play button down and toggling the on button
05. Select Reload Firmware & select Yes to erase firmware.
06. When done, connect with USB cable to computer
07. Open DOS windows into the directory on the computer that contains sendfirm.exe and firmware-zen-beta.nk (navigate to the directory in windows explorer, then keep the Shift key down and right-click in the open area on the right side. From the drop down menu select Open Command Window Here.)
08. In the DOS window type: sendfirm firmware-zen-beta.nk (this is the latest version as of 7/25/16 and is dated 2/10/2014.) When you get a message that the firmware was sent succesfully, close the DOS window.
09. The Zen should now show up as a drive in Windows (if you have an SD Card installed, it will show as 2 drives.) The following refers to the main Zen Drive (it may be easier if you eject the SD Card until you are done so you dont accidentally mistake it for the main drive.)
10. You might get a message from Windows asking to format the drive - if you do then click yes otherwise right-click the drive in windows and select format. Use the default settings to quick format with FAT32
11. Get the latest zen rockbox package at http://www.rockbox.org/dl.cgi?bin=creativezen
. As of 7/25/16, the latest rev is 0f89b04 and package is rockbox-creativezen-20160725.zip
12. Extract the package to the zen drive (it should all be grouped under .rockbox as the main directory - I open the zip file in 7Zip and drag the whole folder over so all I see on the zen drive is .rockbox with everything else stored under that.)
13. When all copied, eject the unit from windows (as you would a normal hard drive i.e. click on the 'Safely Remove' icon on the taskbar) and then reboot Zen (turn off then turn on again.)
14. When all running OK then you can install alternate fonts & themes - to do this shut zen down then connect the USB cable to get into native disk mode. If you connect the usb cable while zen is on it will connect into music copy mode instead.
15. To install themes: go to http://themes.rockbox.org/index.php?allthemes
& choose any of the 320x240 resolution options that look good. They will download as zip files and will have .rockbox as the root directory. Extract these so they merge into the .rockbox structure on the zen drive (I do this by just dragging the .rockbox directory in the zip file onto the zen drive in windows explorer - it then asks if I want to merge with the existing folder and I say yes.)
16. The procedure for installing fonts is similar - get the font pack from http://www.rockbox.org/wiki/RockboxExtras
I hope this helps!