Article is good enough to begin but few points that i want to emphasize :
COM+ services are different paradigm all together w.r.t to any of the other programming language like C# , through which COM+ services can be acessed .
Important thing is that these services can be utilized in the code through either declarative attributes or the implicit code , but assembly can be benefitted at runtime only if it is registered with the COM+ explorer , else it's like any other normal assembly , no matter Sytem.EnterpriseService classes being used inside it .
In your case even if it's a Non .net code used for creating COM+ assembly , then ultimately it's like any other simple communication between .net and that programming paradigm for e.g : COM -> .Net -->
TypeLibrary -> Metadata by creating RCW .
It will only happen at runtime when ur COM+ registered assembly will get loaded then it will start utilizing COM+ services but for .net program communicating with it this doesn't creates a difference .