Until your feature request is filled you might like to look at this - recommended by someone to me on this forum when I did the same thing.
http://www.virtualdub.org/
You can import the file as avi and enter the new frame rate and it does a good job.
I also used a free "Frame Extender" component in Flash for some stuff I had brought in at 12fps.
http://bbs.coldhardflash.com/viewtopic.php?t=214 (bottom of page)
frame rate flexibility
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