New revised how to use a Playstation 3 controller on PC guide.
(Taken from pcsx2 forum.)

Step 1:
Download and install the Xbox360 Controller drivers for your operating system.

Step 2:
Connect bluetooth [skip if you intend to use wired] and your PS3/4 controller to your PC and let Windows install the default driver.

Step 3:
Download and unzip the DS3SCP archive to a temporary directory [eg C:Temp]

Step 4:
Right click the archive and select Properties.

Step 5:
Click the Unblock button if its displayed in the General tab

Step 6:
Unpack the archive.

Step 7:
Create a directory where for the Server to run from [Recommended C:Program FilesScarlet.Crush Productions]

Step 8:
Copy the contents of ScpServerbin to the directory you created in Step 7.

Step 9:
Run ScpDriver.exe

Step 10:
XP/Vista - Check "Force Install" option.
Win 7/8 - Leave "Force Install" unchecked.

Step 11:
Click Install

Step 12:
[For Bluetooth] http://puu.sh/b7RMx/def0f89811.png
If you don't see the install summary on as seen on the bottom of the screenshot, uninstall, check "Force install" and click Install again.

Step 13:
Click Exit.

Notes:
If you have UAC enabled, directories need to be created from an elevated command prompt.
Directories should not be created in "user directories" [eg: Desktop, Documents, Downloads] or on network drives.
To see the status of the controllers connected, run "ScpServer.exe"

Post any issues.

vanelan : I'm glad someone thought of making this guide/post.