S/MIME download and use in IE

I am in the military and have to access email and sometimes send encrypted emails. We use Outlook Web Access and Internet Explorer is the only browser available to use. Unfortunately, Microsoft has control over the S/MIME and it does not work on a Mac through Parallels. Does anyone know how to get the S/MIME running using IE in Parallels, or would Parallels be able to develop this feature? Any assistance would be great as I would prefer not to buy a PC just to send encrypted emails once in a while.