Maybe You shall try another approach - create .sh script, that open Your desired file on browser, then, later on the .sh script, close microB? Then, creating a desktop file pointing to that .sh. Should be much more easier than javascripting voodoo.

Advantage of this method is that You can set every icon You want for every file You wan't - via .desktop file.
Disadvantage is that You need .sh script for every file You want to have @ hildon-home, and You can't delete that .sh after. no big deal, thought - and, You can keep also "template-like" .sh script, where You only need to input path/to/your/file and (optional) icon - setting this would be much faster than bookmarking every file we want.

/Estel