In this article there's the solution I was looking for, however, I would like to open in a new tab instead of a new window, how should be the text?
Google translate client for OS X
...
on run argv
tell application "Safari"
make new document at end of documents
set URL of document 1 to "http://translate.google.com/#en|es|" & item 1 of argv
end tell
end run
...