You are in a dicy situation, the responsive tabs is marked as a system toolkit and the helper code has references to the toolkit name and the zip file and .js file name in it so making a copy and modifying will not be easy, If you have to do it I can give you a starting point you can try the exact change which needs to be made is as follows
find the following section in controls_en.min.js (inside controls.min.zip in script folder)
module.controller("tabs", ["$scope", "$element", "Coach", "$timeout", "coachUtils", function (a, c, d, e, f) {
angular.extend(a, new d(a, c));
a.watchOption("tabActiveColor", "primary");
a.watchOption("tabInactiveColor", "default");
a.watchOption("showBorder", !1);
a.watchOption("selectedTabIndex", 0, , function (b) {
a.setActiveTab(b, !0);
});
and add the last line above for a selectedTabIndex watch which is currently not there, then add the exact same named config option to the copy tab you have created.
Then change the references to " responsive.coaches" in script coachViewHelper under coachview.helper.min.zip to point to the app which contains the copy of the tab control.
add both the above zip (controls.min.zip) files to the app containing the copy of the tab control, change the references to the controls.min.zip to point to the current application version of the zip file
Do not have sufficient time to give you a working example but I hope the pointers are sufficient