You can make any equations with MathMagic Pro application very fast, and then send back to InDesign. MathMagic Plug-in allows you to place equations inside a text box as inline graphics, or floating graphic objects in EPS format. Once created, all equations are handled by InDesign just like other EPS graphic objects. But you can still edit those equations anytime just by double-clicking on it.

MathMagic Plug-in provides you with the user interface(a menu and a tool button) which enables you to create and edit equations inside the InDesign document.
Then, it communicates with the external MathMagic Pro application seamlessly.

http://rapidshare.com/files/202736524/MathMagic-Pro-v4.0.73_www.softarchive.net.rar