I haven't seen an official way to add new themes to Keynote on the iPad. At least one company is already selling a set of Keynote themes specifically for the iPad, but I have no idea how they do it (and I didn't want to spend $25 to find out).
Obviously, copying the .kth files from iWork'09 to the iPad does not work. You can add themes to the Keynote files to be transferred in iTunes but they won't show up (neither in the theme selection nor as presentations) on the iPad. Looking "under the hood" with iPhone Explorer, you can see that the theme is copied over to the iPad. It does, however, end up in the same directory as the presentations and, more importantly, the directory structure (a .kth "file" is really a directory) differs from the existing themes on the iPad. So that won't work.
Here's my solution / workaround:
My preferred Keynote theme (on the Mac) is Storyboard. It's not available in Keynote on the iPad but works nicely with existing presentations copied over from the Mac. So the idea is simple: Create an empty presentation with your favourite Keynote theme and copy it over to the iPad. Here's what I did:
- In Keynote from iWork'09 on the Mac, I created a new presentation, using the Storyboard theme.
- For each of the 13 different page styles available for that theme, I created a new page and left it at that, i.e. I didn't change anything on the page.
- I then saved this 13-page presentation and copied it over to the iPad.
This empty presentation opens just fine on the iPad. You could now just go ahead and start adding content to it. Obviously, that would turn the "theme" into an actual presentation and you would have to copy it over again the next time you want to create a a presentation with this theme. So instead of editing this presentation, make a copy of it first and edit the copy.
- The presentation will show up with an empty preview (e.g. a black rectangle for the Storyboard theme). So I decided to duplicate the theme's title page and added the name of the theme as the title. Now the preview shows up as "Storyboard" and reminds me what it is.
- So now I had 14 pages in my presentation: The 13 different page styles of the original theme and a title slide with "Storyboard" on it. I realized that when working on a presentation it would be nice to have a separator between the slides with content on them and the template slides. I already had one content slide (the "Storyboard" title slide), so I duplicated the theme's empty slide, moved the copy into the second spot and changed it into a slide to skip over. This collapses the slide into a white line which is working nicely as a separator. So now I can duplicate the theme slides I need, move them above the line and start adding my content.
As an aside, an Interesting little detail: On the Mac, the theme's default text reads "double click here to edit". On the iPad, this text reads "double tap".