Felix,
You might consider to replace the crushed sleep/lock button.
Which generation of iPod is it? I know that the iPod touch 4G does not have such a sleep/lock button. So you must have an older version.
In any case, I think the only way to replace this button is by disassembling the iPod.
However, I can only speak on the basis of my experience with an iPhone 3G that I completely had to disassemble in order to get to the volume/sleep button. So I don't know if you actually have to disassemble the whole device before you can remove the crushed sleep/lock button and built in a new one.
I hope this helps.
Steffen