Convert Project "PagSeguro" to work in Medium Trust Level ASP.NET

I have a project ready and working integration with a payment site called PagSeguro of Brazil, it works like PayPal. It is written in C # and currently works only on IIS servers with ASP.NET Full Trust of Level enabled. I need it to work in Medium Trust Level, but I can not change the server configuration, for I am hosting on shared server. So we need the project to be adapted to work in Medium Trust Level. Error Explanation: This project currently enables me to do the clear payment (without leaving my system). The error occurs when clicking on pay and call a method, you can not open a popup in the browser and ero this is due to the confidence level I have all the files and source code to perform this adaptation.