But, from a native thread I can use System::Threading::Thread to get a managed thread id and an AppDomain id so I'm hopeful that I can somehow manually move a thread's execution into a specific ...

You can create a new application domain using one of the overloaded CreateDomain methods of the System.AppDomain class. Note that all of these methods are static hence you can invoke them sans the ...

AppDomain.CurrentDomain.AppendPrivatePath(ThirdPartyToolsPath); //The below isn't neccessary, nor does it fix the problem // I'm just including it to head-off anybody suggesting ...