How to simulate an axis through script?

I am trying to modify someone's code who had the bright idea of using the Unity built in input manager.

I was able to fix the buttons to my liking, by sifting through a list of strings for the correct binding, but I have no idea what an axis is in the first place, let alone how to create a function to handle a situation in which an axis was used.

Specifically, I need a way to turn "W" and "S" into "forward" and "backward", and what that would translate into with regards to "GetAxisRaw()".

I know that it's a float number, but I have no idea how I would simulate it....

Here's the code I wish to modify:

 #pragma strict
 var key : String;
 var input : InputItem;
 
 function UpdateInput () {
     //Just get the axis value from Unity's input
     input.axis = Input.GetAxisRaw(key);
 }
 
 //I'm not a big java fan, but in the interest of keeping everything within the asset working, I'd appreciate an answer here in java.
 

Here's an example of the code I use to pick a button out of an array:

     public static KeyCode getKey(string key)
     {
         int keyint = 0;
         KeyCode returncode = KeyCode.A;
         for(int i=0; i<End; i++)
         {
             if(bindsnames[i] == key)
             {
                 keyint = i;
             }
             else if(i >= End)
             {
                 Debug.Log("ERROR 2: The key you are trying to access does not exist");
             }
         }
         returncode = (KeyCode)Enum.Parse(typeof(KeyCode),binds[keyint]);
         return returncode;
     }

I'm not a very advanced programmer (could you tell) so baby steps would be appreciated. I work mainly in C#, but in the interest of not breaking the asset I am attempting to modify, I'd prefer an answer which uses a function I can then call from the javascript.

I do not want to use the Unity input manager. I have many reasons for this but mostly because you cannot change the values at runtime.