Change directory to one level above the 'disk' subdirectory, of course after you've inserted a SD device into the O2+. Type the following commands:
The first command, the one with the leading period, simply brings the file and all of it's variables and functions into your current shell. The second command runs a function, coincidentally of the same name as the file. The function will call a number of other functions that will set up the device for use as expanded storage as well as allocate and enable swap space.
This works well if executed from the "proper" directory installing a whole system for my project (which you don't want). If it fails it may just because I'm playing fast and loose with directories here. Let me know if it fails and I'll analyze.