for better 'sharing' :

This steps are tested in image OpenPli 4.0 on dm800hd , dm800se and dm500hd , but should work in every dm model , you need an usb pen already mounted on box , mounted on default /media/usb/ path
1) in telnet send command to stop enigma2 process
Code:
init 4

2) send command to remove older lib on usb(if you already do this process with last image)
Code:
rm -Rf /media/usb/lib

3) move usr/lib to usb
Code:
mv /usr/lib /media/usb

4) link usb/lib to default system path
Code:
ln -sfn /media/usb/lib /usr/lib

5) restart enigma2 process
Code:
init 3


Now you have all lib folder on usb and save 40% free space in flash

I tipically use this kind of way when i want to test every plugin etc... on new images ...