Launch mime type - like excel, pdf using LinkToUrl / LinkToAction

Hi,

I have uploaded excel (demo.xlsx) and pdf (dmo.pdf) files in mime and I wish to launch it (show standard popup with buttons open, save and cancel). How do I achieve using

LinkToUrl (what should I put in reference field)

LinkToAction (Needed code to read from mime and launch it)

Thanks

Amit kumar Jain