What I did before when I wanted to add PDF viewer:
1. Download and temporary install Chrome portable package from PortableApps.com
2. Copy pdf.dll file from the Chrome folder to folder where iron.exe resides
3. Remove the Chrome Portable
I'm not sure if it will work for you, but it's not too hard to try...
, thank you for the note. It's updated now.--
Keep it simple, it'll become complex by itself...