Greetings! As far as I can tell, the part number you're looking for is:
1123-182-1505 (It's listed as "Throttle Rod".). Be warned, I'm looking at a January 2003 version of the Stihl SCS. I don't *think* the o21 has changed. Of course, it might be called the MS-210 by now! :)
To answer your other question, the part is held in place by it's shape. No clips, springs, or what have you. IMHO, find a coat hanger and bend away! But if you *want* a genuine part...It's probbably not very expensive. Hope this helps!
Hal