This is intended to be used with DSfix. After installing DSfix...
In DSfix.ini, find this line:
dinput8dllWrapper none
Make it look like this line:
dinput8dllWrapper dsmfix.dll
Then, unzip dsmfix08.zip; place all dsmfix* files in the DATA directory (~Program FilesSteamsteamappscommonDark Souls Prepare to Die EditionDATA).
Finally, open dsmfixgui.exe and make the desired adjustments (mouse over an option for relevant tooltips); or, edit dsmfix.ini by hand.
For additional information, please see http://www.cs.wisc.edu/~petska