1. A computer-implemented method for changing the operation of an application, wherein the application is associated with a first dynamic link library, comprising: launching a user process associated with the application in a suspended mode; writing an asynchronous procedure call to the user process, wherein the asynchronous procedure call associates the application with a second dynamic link library when executed; and thawing the user process such that the asynchronous procedure call is executed and the operation of the application is changed according to functionality provided by the second dynamic link library.