ActiveX webservice library interop from C# winform

Question

Hi C-SharpCorner,

I have had this issue for over a month already and have yet found a solution. A client of mine has asked me to write an application using .NET C# (4.0) for buying and selling stocks. The application is basically complete, less this issue I'm encountering. Before an order can be submitted to their servers, the order (message in ascii format) must be signed with a hash algorithm, and further encrypted with a private-key. I have already spent the past month learning all I can about public-private-secret key encryption, RSA, DES, etc.., but without resolve. I have recently learned their encryption algorithm uses the SSL library, which in turns uses the DES encryption. Therefore without a known IV, there is not much I can do to try and encrypt the order-message manually.

The next step in finding a solution is to use a library provided by the client. The package I received is a .cab file containing various .dlls (axekey.dll, cryptoki.dll, pkns32.dll, and taica.dll), and an .inf file. I am told this library is actually an ActiveX web-service library, and must be installed on (I suppose) a web-service, like IIS

Here is the issue I am having: it is unlikely for the users of my winform to have IIS installed, and even less likely to have them installed as a program requirement. What I want to do is be able to interop directly into the axekey.dll and call the functions directly. The only documentation I have in this regard is usage through web-requests (ie. ../cgi-bin/ekey/axekey.cab#)

Is what I am proposing even possible?

What are the possible avenues I should be investigating?

So more additional info:
By using a tool called PE-Explorer, I was able to find a lot of information about this dll, including its imports and exports. For its exports, I can see the following information: DllCanUnloadNow, DllGetClassObject, DllRegisterServer, and DllUnregisterServer. From what I understand, there are not the methods (or entry-points) I should be using from the C# interop.

Furthmore, by using the MS tool tlbimp, I was able to create a CLI wrapper for this library (axekey.dll), the output is called SYSORDERLib.dll of which a whole host of information was further discovered; including: something called CoClass, some Dispatch, a bunch of GUIDs, functions, properties, etc.

Now I really just want to know, how should I DllImport into this information?

Further info can be supplied upon request. There is just too many reports generated by PE-Explorer for me to post everything here.