Insert Equations in Excel 2010 using C#

Hi, I should start by saying I don't think this is possible. But I'm placing a suitable reward up for anyone who can demonstrate a solutions. The challenge is I want to use C# to insert what microsoft call "A common mathematical equation" into an active spread sheet. You can find this in Excel 2010, under the 'Insert' ribbon, with the pi symbol. NOTE: This is not about inserting a formula into an excel cell. Rules: 1) To demonstration the approach your code should contain a popup into which I can type text (MATHML or otherwise) for the equation, it should then use this text to generate the natural looked equation somewhere on the spread sheet. 2) The system can not use any external web services or other external programs to Excel. 3) The solution should be written in C# (or another .NET language) and compiled to create an Excel addin. 4) You can not over right the xls spread sheet file then force a reload of the page in Excel. Good luck