Ok, I found this information which seems detailed enough...
Create a partition
Goto FileBrowser > MISC > HDDmanager (wait for HDD module to load if HDD isnt started already)
Press R1 and a context menu will open
Select Create , press O and a virtual keyboard will open, input the name OPL, select OK and press O
a partition size selection menu will open. Choose from 128MB to 128GB by pressing <L R>
Now give some thought before setting the partition size, the maximum amount of games that can be listed on a HDD is 256 and if you saved a 8MB VMC for each game, then 2GB would be the Max size for VMC use , but now consider if your going to use ART and Themes from the HDD too. You will need to look at how much space all your Art/Themes use and add that amount to make sure your partition will have enough space for all your needs.
Press once you have chosen the partition size you want and a confirmation box will open, press O on OK to begin creating the partition.
You will see +OPL listed once the process is completed.
Copy folder to the partition
To copy your ART folder, just use FileBrowser > hdd0:/ and you will see the +OPL listed there to copy it into.
The VMC folder will be created there by OPL when you create a VMC file from the HDD Games list or you can create it if you want with uLE, while your in the partition.
However, one more question, on my Windows, Linux, or Macintosh machines, creating or changing partitions can mean the death/erasing of all data and necessitate the recreation of any other already existing partitions. That is not the case here? Or is it? In other words, will I need to reload all my games again if I do this? Are there any other side effects?