CQG API is available as 32-bit and 64-bit COM server.
How to specify the version you want to use in the client code?
In most cases there is no special work is required. The COM will try to match CQG API server architecture to the client architecture. In other words, for a 32-bit client, COM will activate 32-bit version CQG API server; otherwise it will activate a 64-bit version of the server. Therefore, if the client code should use CQG API 64-bit version it should be built for x64 (Any CPU) platform.
Samples of CQG API 32-bit and 64-bit versions usage in the client code can be found on API web page.