Detecting installation of the SVG Viewer
To detect the SVG ActiveX Control, the control name for the plugin is "Adobe.SVGCtl".
AutoInstall and Detection Scripts
Adobe has also provided plugin detection scripts, which are available at:
http://www.adobe.com/svg/workflow/autoinstall.html
Note: The script code uses:
isSVGControlInstalled = IsObject(CreateObject("Adobe.SVGCtl"))