How do I deal with events containing parameters?

I have a .tlb that originated from a C# .net dll that gives me the following

// *********************************************************************//
// OLE Server Proxy class declaration
// Server Object    : TDesktopClient
// Help String      :
// Default Interface: _DesktopClient
// Def. Intf. DISP? : No
// Event   Interface: IClientEvents
// TypeFlags        : (2) CanCreate
// *********************************************************************//
  TDesktopClient = class(TOleServer)
.... and so on

where OnContactData is defined in the .tlb as
property OnContactData: TDesktopClientContactData read FOnContactData write FOnContactData;

and TDesktopClientContactData is defined in the .tlb as
TDesktopClientContactData = procedure(ASender: TObject; const data: _ContactData) of object

and FOnContactData in the .tlb as
FOnContactData: TDesktopClientContactData;

So as far as my understanding goes I will need to add the following to my own form,

TDeskTop:= TDesktopClient.Create(self);
TDeskTop.OnContactData:=Call;

The question is really, how do I deal with the OnContactData in a way that I can access the _ContactData parameter?

(My guess is that I need to create something similar to .OnContactData but I am not sure exactly how I would do this to access the _ContactData object.)