Sorry... I got another little question.
The answer is you can add them, because the form is there on the right side of the screen, but it doesn't save them.
I'm building an album of albums, so the "search" box will only search within this album, not within the sub-albums at other URL's.
As the master album is made up of all web-location pages, I was hoping I could add the keywords on these pages, so that I could query "show me all albums that contain photos of Stockholm" for instance.
I can add those keywords to the "comments" at the bottom of the page, but then they all show up on the generated screen, which may or may not be OK, I haven't decided yet.
This might sound odd, but add the keywords in the Explore mode (thumbnails). See the "Keywords" button on top right. In Edit mode jAlbum tries to save the keywords as XMP tags, which is not available for web locations. David - jAlbum author - is working on a solution to circumvent this.