アップルスクリプトはド素人なんですが・・
いろいろやってたらこんなんできますた。ダメ？

tell application "Finder"
set file_list to selection
set iend to count of file_list
repeat with i from 1 to iend
set the_file to item i of file_list as alias
set name of the_file to "test_" & i
move the_file to trash
end repeat
end tell