I have a running Inno Setup script, wherein I use innocallback.dll by Sherlock Software.
This DLL wraps a procedure of mine so that it can be passed to a C# DLL.
With Inno Setup 6, there's built-in CreateCallback function that serves the same purpose as WrapCallback function from InnoTools InnoCallback library.
WrapCallback
So you can now do:
Test(CreateCallback(@mycallback));