Ok, I found a way to do it, perhaps just getting used to the new gallery feature in 3.5.  Here are the steps I used for my gallery page, which has the [juicebox gallery_id="1"] code in it.

* Edited the page in which the Juicebox gallery exists and selected the Add Media button.
* Selected the Media Library option for Insert Media.
* Selected Uploaded to this page from the drop-down list.
* Used drag 'n' drop to reorder the images.
* Clicked Insert into page.  This may not be necessary but I used it to ensure ordering changes were saved.
* Deleted the inserted Wordpress gallery.
* Updated (republished) the gallery page, which only has the juicebox code in it.

This seemed to update the Juicebox XML and display the images in the correct order.

If there is a better way, please let me know.

Yes, using the Shiba Media Library plugin mentioned above.  However, while I managed to make it work, I am still not sure about the long term trade-offs.

Essentially the Shiba Media Library plugin enables you to deattach an image from a post and attach it to another.  I had Media Library images already attached to pages, which I subsequently wanted to include in a gallery of software application screen shots.  I didn't want to upload the same screen shot again.  www.recollx.com

What I did was detach the image from the original page and then attach it to the image gallery page.  By resaving the Juicebox gallery settings, the XML gets updated with the newly attached image.  While the image remains in the original page, as far as I'm aware it is no longer linked to the Media Library.  This may mean that updates to descriptions in the media library will not propagate automatically to the original page where the original image remains.

Still being new to WordPress, I have to confirm if that is in fact the way Media Library works... i.e. does updating the image info, such as a caption, in the media library automatically update what is shown on a page which already has that image attached?  I'll have to test.

I think the problem I'm running into is that I'm a WordPress newbie.  It appears that you cannot attach a single image to multiple posts?  Like many I've seen in the WP forums, I want to upload a single image and use it attached to multiple pages/posts, one of them being the Juicebox gallery page.  Below is an example.

http://wordpress.stackexchange.com/ques … ve-gallery

One of the forum posts I read about suggests this plugin: http://shibashake.com/wordpress-theme/m … us-plugin.

While I'm not sure whether this will do what I want yet, do you know already if this would conflict with Juicebox?

Update:

I've installed the Shiba plugin and it does not seem to conflict with Juicebox.  I managed to attach an existing Media library image, which was already attached to another page, to my gallery page.  After editing the Juicebox gallery and saving the settings (with no changes), the image appeared in my Juicebox gallery and remained visible on the original page.  A problem I see is that the media library reports only one attached page (the gallery page now) for the image.

I'm not sure yet about what disadvantages may arise from this approach.  I just think uploading multiple image copies is very inefficient for storage and management.  I'm using Juicebox for display software screenshots and those same screenshots appear on other pages in conjunction with explanatory text.