My understanding is you can use whatever to create whatever and use whatever you created. For instance, consider the dll file that you are interested in using to manage window handles. I believe this was created using c++, but don't quote me on that. there is an API offered that you can gain access to this dll via an entry point. I say use VBA to access the file and place the code in a standard module. You could also use a custom class. Either way, you can place the module(s) in an Access file and reference the Access file. You can use the Add In manager within Access to look for an Access File with the accda extension. I never used the Add-In Manager, but you might want to give it a go.
I say place your Class library in an accde and reference that. This way, the VBA is removed and would be more difficult to reconstruct human programming language.
Here is an example of using an API to get at the System Clock. The keys are, identify a name for your sub-procedure, identify a name for your function, identify the appropriate dll file, and identify the entry point for the dll file.
Code:
Option Compare Database
Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)
Public Sub PauseCode(MillisecondsCount As Long)
Sleep MillisecondsCount
End Sub