<b>Q. How can I create a partition on my SD card? </b>
If you have a custom recovery installed (ClockworkMod or AmonRa) on your phone you can use it to create a second partition on your SD card.
Or you can use a computer to create it;
- on Windows there are some free partition manager applications such as “MiniTool Partition Wizard Home Edition”, “EaseUS Partition Master Home” etc. You can use any of them that you prefer.
- on Linux you can use GParted.
- on Mac OS you can use its Disk Utility.
here is another tutorial http://forum.xda-developers.com/showthread.php?t=2142844