-- change line below to the right name and location where you saved your .workflow
set workflowpath to "LeopardFirewire:Users:test:Desktop:New PDF from Images.workflow"
set qtdworkflowpath to quoted form of (POSIX path of workflowpath)
set theExtensionList to {"jpg", "png", "tiff", "pdf"}
set theFolders to choose folder with multiple selections allowed
repeat with aFolder in theFolders
set theInputList to {}
tell application "Finder" to set theFoldersContents to (every item of aFolder whose name extension is in the theExtensionList) as alias list
repeat with anItem in theFoldersContents
set end of theInputList to quoted form of POSIX path of anItem
end repeat
set {tid, AppleScript's text item delimiters} to {AppleScript's text item delimiters, linefeed}
set theInputList to theInputList as text
set AppleScript's text item delimiters to tid
set command to "/usr/bin/automator -v " & "-i '" & theInputList & "' -D OutputFolder=" & quoted form of POSIX path of aFolder & " " & qtdworkflowpath
set output to do shell script command
end repeat
return output