Use the AQB.Web.QueryBuilder.GridComponent.customEditControl event for this purpose. Below is the sample handler that changes the editor for the "Column name" (Alias) column to a combo box and prepopulates it with the predefined values.

<script>
    AQB.Web.onApplicationReady(function(qb) {
        qb.GridComponent.customEditControl = function (key, cell, row) {
            var control = null;
            if (key == qb.MetaData.FieldParamType.alias) {
                var values = ["alias1", "alias2", "alias3", "alias4"];
                control = $('<select>');
                values.forEach(function(val, i) {
                    $('<option value="' + val + '">' + val + '</option>').appendTo(control);
                });
            }
            return control;
        } 
    });
</script>