JavaScript - How do I call a function from a string name and pass an array object?

I've got a user control which lets users provided their own script names that are called by the control on specific events.

I have the following code:

initialize : function()
{

    // Call the base initialize method
    Point74.WebAutoComplete.callBaseMethod(this, 'initialize');

    $(document).ready(
        Function.createDelegate(this, this._onDocumentReady)
    );

},

_onDocumentReady : function()
{
    var me = this;
    $("#" + me.get_id()).autocomplete(me.get_ashxAddress(), 
        { 
            formatItem: function(item)
            {
                return eval(me.get_formatFunction() + "(" + item + ");");
            }
        } 
    ).result(me.get_selectFunction());
}

me.get_formatFunction contains the name of a function, i.e. "FormatItem". This example is currently using eval, which I do not want to use... plus this example doesn't work anyway, but I thought I'd show what I'm trying to get at.

In the example above, I get a value undefined error as 'item' is a string array and eval tries to convert it into one long string.

How can I achieve this functionality any still pass through 'item' as a string array to the named function?

If passing named functions is a bad idea, are there any alternatives?

This is how my control is declared:

<p74:WebAutoComplete runat="server" ID="ato_Test" AshxAddress="WebServices/SearchService.ashx" 
     FormatFunction="formatItem" SelectFunction="searchSelectedMaster" />

me[me.get_formatFunction()](item);