You're probably thinking of the "Career Adjustor" which lets you choose any job level (up or down) or increase or decrease job performance, among other features.
It is not a separate item, but a feature of the Insimenator, found right on the main forum page (last item listed under Community Downloads).
Note that Insimenator is no longer supported. That doesn't mean it no longer works, just that problems (if any) with using it won't be addressed.
A different which can be helpful in getting promotions faster is the "No Friends Needed" mod, here:
http://www.simbology.com/smf/index.php?topic=15.0.