Enter Variable into Text or Number Field

Perfect!... Here is my updated code with an "If then else" to change the name of the last piece of room tone to "_Fill". I have also added a hack to get the Min:Secs entry into the "Edit Loop Selection" (It seems that it wanted an extra "0." before it would accept the Minutes, Seconds, Miliseconds.

//This script will cut up room tone lengths from a piece of clean room tone that is longer than the largest array value.

//Set Variable Array for room tone Clip lengths.
var loopLengths = [
    '0.00.400',
    '0.00.500',
    '0.00.600',
    '0.00.700',
    '0.00.800',
    '0.00.900',
    '0.01.000',
    '0.01.100',
    '0.01.200',
    '0.01.300',
    '0.01.400',
    '0.01.500',
    '0.01.600',
    '0.01.700',
    '0.01.800',
    '0.01.900',
    '0.02.000',
    '0.02.500',
    '0.04.000',
    '0.04.000',
];

//Create variable for Min:Secs input into Edit Selection Length field. (Till Bug is fixed)
var timehack = '0.';

//Activate Protools Main Window
sf.ui.proTools.appActivateMainWindow();

//Set main Counter to Min:Secs view
sf.ui.proTools.mainCounterSetValue({
    targetValue: 'Min:Secs'
});

//Create loop for the Array
for (var i = 0; i < loopLengths.length; i++) {
    var loopLength = loopLengths[i];

    //Check if user cancelled our command. This will stop the script if the user cancelled
    sf.engine.checkForCancellation();

    //Select the Edit Selection Length Field
    sf.ui.proTools.mainWindow.groups.whoseTitle.is('Counter Display Cluster').first.textFields.whoseTitle.is('Edit Selection Length').first.elementClick({});

    //Enter Array variable into "Edit
    sf.keyboard.type({
        text: timehack + loopLength
    });

    //Press return to make Edit Selection Length accept loopLength
    sf.keyboard.press({
        keys: "return"
    });

    //Enter Array variable into "Edit Selection Length" (Disabled this step till bug is fixed)
    //sf.ui.proTools.selectionSet({
    //    selectionLength: loopLength
    //});

    //Press the Menu Item for renaming clips.
    sf.ui.proTools.menuClick({
        menuPath: ["Clip", "Capture..."],
    });

    //Define "Name" window variable
    var nameWindow = sf.ui.proTools.windows.whoseTitle.is('Name').first;

    //Wait for the "Name" window to appear:
    nameWindow.elementWaitFor();

    //Lables the last array item as "_Fill"
    if (i == loopLengths.length - 1) {

        //Enter "_RT " and Variable into "Name" window text field.
        nameWindow.groups.whoseTitle.is('Name').first.textFields.whoseTitle.is('').first.elementSetTextFieldWithAreaValue({
            value: '_Fill',
        });

        //Click OK
        nameWindow.buttons.whoseTitle.is('OK').first.elementClick();

        //Wait for "Name" window to disappear
        nameWindow.elementWaitFor({ waitForNoElement: true });

    } else {

        //Enter "_RT " and Variable into "Name" window text field.
        nameWindow.groups.whoseTitle.is('Name').first.textFields.whoseTitle.is('').first.elementSetTextFieldWithAreaValue({
            value: "_RT " + loopLength,
        });

        //Click OK
        nameWindow.buttons.whoseTitle.is('OK').first.elementClick();

        //Wait for "Name" window to disappear
        nameWindow.elementWaitFor({ waitForNoElement: true });
    }
}

My next step is to get the room tone and fill to export and reimport as whole audio files.

Thanks a million for your help Christian :-)