I have added some custom actions that are written in C#. They are called at the correct points and execute as expected until I call code in other DLLs in the assembly. IS can't resolve the reference, i.e. can't load the other DLL.
There's also some options you can set in the ISCLRWrap table to have InstallShield's managed custom actions explicitly pull in dependent assemblies. The sample document http://community.installshield.com/attachment.php?attachmentid=7220&d=1217951981 talks about this - search for Dependency0 within the document for an example.
With DTF you simply add your dependencies as assembly references or project items. If you need your files nested, you just create project folders and put them in there. Managed or unmanaged it doesn't matter, you'll have all of your files right there with your CA and the working directory set to the root.
I'm glad Installshield pioneered the Managed Custom Action support, but the reality is Microsoft's DTF solution is far superior, free, open source, integrates with InstallShield easily and yet doesn't lock you into InstallShield.
