You can view html files offline. That is how I have my 8830's Homepage setup - an html file I created and store on my SD card.
I did not "save" the file from an online site but created it on my computer and placed it on the sd card. So I'm not sure how to save a page to the card from the BB's browser.
The way to reference such a file (turning on my bb and seeing if I can find the reference.....) without the quotes:
"file///SDCard/Blackberry.html"
So, if you can save the file your's might be something like
"file///SDCard/BoardingPass.html"
If internal memory, you might just drop the "SDCard" part but I have not tried that.
PS: I had thought of doing this for my recent trip to Europe but NW airlines would not process my pass - probably since it was a out-of-country flight and you need to be seen with passport. And like you, I was worried about trying it the first time anyway when I logged on to even try it.