3.5 hard drive mod
 

http://www.amazon.com/gp/product/B00...ef=oss_product
Here is the link to get the cable you will need.
3.50

Then you can use an external power source.
You can make one or just order one.
http://www.amazon.com/Drive-Adapter-...6534770&sr=1-8

7 bucks

https://picasaweb.google.com/midwest...11462765762450

Here are some pics. You need to modify the connector a bit and the clip inside the ps3. Both mods are shown in the pics.

Now. I was thinking of using the 12v line off the psu. However it is known that the power supplies are kinda crap on these things.

Any thoughts?

Also there might be a way to fit this in the case but again the heat and power draw might create a problem.