You dont have to use a plugin
Copy the folder
/usr/lib/enigma2/python/Plugins/Extensions
to /media/usb or /media/hdd
Delete the folder Extensions from its original place folder /Plugins
using dreambox control centre make new symlink in folder /Plugins
right click select new symlink
for usb type
target : /media/usb/Extensions
name : Extensions
for hdd type
target : /media/hdd/Extensions
name : Extensions
reboot