YES you can but it is not an install as you might think off, you can however use Safari bookmark feature to save a bookmark to your app on your iPad home, then when you click that bookmark from your home screen the app will show up without navigation bar and browser oeverhead, it will look exactly like a native app, this is how to do it:
http://stackoverflow.com/questions/6011223/how-to-completely-hide-the-navigation -bar-in-iphone-html-5
However, I believe Apple did find a way to emputate HTML5 app on home screen and I heard they might also be messing with offline cache. You will have to do your own researches but this article is a good source of information:
http://www.theregister.co.uk/2011/03/15/apple_ios_throttles_web_apps_on_home_scr een/
I personally build all my apps to be cross platform and I use Adobe Flash Platform and AIR, my apps work on the web everywhere (except iOS0, as native app everywhere (including iOS), on desktop (Mac, PC and Linux) and on a wide range of smart tvs, all with one source code base. I would not touch HTML5 and its cross browser nightmare even if I was paid double!
Note to moderator, please refrain from deleting this post and my entire account again for telling the truth!