If you have Microsoft Office you can export a Word outline saved as .rtf , import it into Powerpoint and then open the Powerpoint from inside Keynote. It might work saving the Pages file in Word format and going from there.
It is a little complicated but once I worked out how to do it worked every time. It is a little different for Keynote 6 and 5.
In your Word document you need to apply styles so that when you import the text into Keynote they map like this:
Heading 1 = Title
Heading 2 = Body level 1
Heading 3 = Body level 2 etc
The system reads the file and wherever it finds a Heading 1 it makes a new slide. So for every new slide there must be a Heading 1 element, even if it is just a placeholder which you change or delete later.
Keynote 6:
Prepare a Theme with the styles you want and drag the slide Master that most slides will use to the top of the list of Masters. Save the Theme (Save/Save theme). It will appear under My Themes in the Theme chooser.
1 Save Word outline as .rtf (important!)
2 Open Powerpoint
3 Choose menu item Insert/slides from outline
4 Save the Powerpoint file
5 Open Keynote
6 Select File/Open and open the just saved ppt or pptx file. (You can open Powerpoint files directly into Keynote)
7 Choose the Theme you want (File/Change theme)
8 The slides will now all have the first Master in the list; apply different Masters to slides you want to change
Keynote 5:
1 Save Word outline as .rtf (important!)
2 Open Powerpoint
3 Choose menu item Insert/slides from outline
4 Save the Powerpoint file
5 Open Keynote
6 Select File/Open and open the just saved ppt or pptx file. (You can open Powerpoint files directly into Keynote)
7 Copy some slides from another presentation with the format you want into the Keynote file (or construct new masters as you wish them)
8 select all the new slides you have just imported and apply the master you want (the fonts, etc, won't be as you want them.)
9 select all slides and then select Format/Reapply master
10 By default if you open a Powerpoint file it may copy videos and audio into the file and you can't then change this. If you don't want this, copy slides back into a file which has been saved with external audio and video.