[Kingofl337]

Here is the easiest way to do what you wish.
1.) Right click on User Functions -> Add New -> Name it omni and click ok
2.) Click on the project tab.
3.) Right Click on the function name -> Convert to 'C' Code -> Yes
4.) After you function will look like this....

#include "Main.h"

void omni ( void )
{
<---Paste the code in here
}

5.) Paste the code provided between the braces starting at the variables and ending with the last brace.
6.) Rename SetMotor to SetPWM
7.) Goto the UserInclude.h File and under where it says "Add User Code Here"
Add a line : void omni (void );


This should work, I tested it out.