Batch file processing with non-scripting app (Preview)

Question

Well I RTFM and spent MANY hours on macscripter et al, the answer is just not going to come to me. I have some RAW files in an obscure Canon format that is only recognized by Preview, which is not scriptable. I'm dealing with hundreds of files from a stop-motion animation project so batch-processing is a must.
The Goal: Individually open several hundred RAW image files in Preview, then save them as .PICT files in a new directory.
Automator doesn't want to play - it simply refuses to do this as a batch job, so I'm left with manipulating the UI through Applescript. Below is what about 10 hours of head-beating has produced:
-- Start Finder tell block
tell application "Finder"
--Pick files to convert
set SelectedFiles to (choose file with multiple selections allowed)
set filesList to get every file of SelectedFiles
--Begin repeat loop for every file in selection
repeat with aFile in filesList
set theFile to aFile as alias --Set theFile as current target
tell application "Preview" --Open Preview, open the target file
(activate) and (open theFile)
end tell
--Need to manually select "save as PICT", so this opens the prompt
tell application "System Events"
keystroke "s" using command down and shift down
end tell
--Buy some time for the conversion and save process
--(there has GOT to be a better way!)
delay 30
end repeat --loop (with fingers crossed)
end tell
This is a HUGE advance from where I started, trying to repeat for "every file in folder..." which just ain't gonna work on my computer. But, it doesn't do anything beyond getting a list of input files. My output is below:
tell application "Finder"
choose file with multiple selections allowed
{alias "Macintosh HD:Users:mark:Pictures:LEGOS:IMG_0126.CR2", alias "Macintosh HD:Users:mark:Pictures:LEGOS:IMG_0127.CR2", alias "Macintosh HD:Users:mark:Pictures:LEGOS:IMG_0128.CR2"}
end tell
Thanks, my head hurts now. (Why couldn't they just have ported REXX???)

Answer 1

Hiroto, no I didn't have it checked. I don't know why I was able to get as far as I did but enabling access for assistive devices didn't change anything. I am able to emulate /almost/ any keystroke, except the up arrow, which normally allows me to move up in the "file type" selector button. The script below is ... functional ... except that it forces me to save each file as a 58MB uncompressed .tiff, and it refuses to respond to the "close front window" or 'keystroke "W" using command down' scripts. Getting through 300+ files this way will eat up my memory and hard drive in a matter of minutes. I suppose I could '$sh kill ####' from terminal if I could find the window process, but this is getting really hoaky!
THIS SCRIPT OPENS AND SAVES FILES, BUT DISALLOWS ANY TYPE SELECTION OR CLEANUP
set sFiles to (choose file with multiple selections allowed without invisibles)
repeat with aFile in sFiles
tell application "Preview" to run
tell application "System Events" to tell process "Preview"
tell application "Preview"
activate
open aFile
delay 8
tell application "System Events"
keystroke "S" using {command down, shift down}
delay 2 -- opens save as sheet
repeat 7 times
keystroke tab -- tab down to file selector (works fine)
end repeat
click down -- select button (doesn't do anything)
delay 1
keystroke up -- open file button menu (doesn't work)
keystroke up -- select next menu item above (doesn't work)
keystroke return -- shortcut to "save" button
delay 10 -- wait for save
keystroke "W" using command down -- close current window (doesn't work)
end tell
end tell
end tell
end repeat