I’ve now managed to get Dropbox syncing to the SD card on my HP Elitepad, following the same instructions I used for SkyDrive, namely:

  1. Format the MicroSD card as NTFS (otherwise this method will not work).
  2. Create a Folder C:Data
  3. Create a mount point for the MicroSD drive as C:Data on the fixed drive.
  4. Install Dropbox Desktop and supply C:Data as the Dropbox folder.
  5. Dropbox will create a dropsub dir and start syncing to your SD card