.Net UserControls does not download when .Net 4.5 is installed

We have a web application that downloads a DLL file into the Temporary Internet Files folder via the HTML Object tag, like the line below.
<OBJECT id="scan_obj" WIDTH=0 HEIGHT=0 classid="NameOfFile.DLL#ActiveXSourcing.Control"></OBJECT>

Once the DLL file is downloaded, we use Javascript to make calls from the web app down to the local DLL.   The DLL is used to make API calls to various devices on the client that are used within the our web application.

Our web application works like a charm until you install .Net 4.5 on a Windows 7 machine or if you use Windows 8 (since 4.5 comes with Windows 8)

After installing .Net 4.5, I've found to make our web application continue to work as currently designed, that you would need to do the following: 
1) Enable 3.5/2.0 .Net Framework
2) Add a registry entry named “EnableIEHosting” to these locations and set the DWORD value to be 1.    
o 32-bit System: HKLM\SOFTWARE\MICROSOFT\.NETFramework
o 64-bit System: HKLM\SOFTWARE\Wow6432Node\Microsoft\.NETFramework

I also found that .Net UserControls like this does not work in IE when .Net 4.5 is installed.  That can be found by going here http://msdn.microsoft.com/en-us/library/hh367887.aspx and scrolling down to the Web Applications section.  It can also be found here:  http://stackoverflow.com/questions/12109642/loading-net-usercontrols-in-ie-with-net-4-5

When using Windows 8, we would prefer to not require our customers to have to enable 3.5/2.0 and having to add the registry setting in order to use our web application. Of course, we would also not have to have our customers edit the registry if they install .Net 4.5.   

What can we do in our code in order for our web application to continue to use Javascript calls to make calls to a DLL that will then in turn make API calls to our various devices on the client and the web app will continue to work?