When you set make a bounty, you're allowed to pick one of several bounty reasons.
You're also granted a free form box to write things out in greater detail.
So, yes: you can set "whatever" requirements you'd like on your bounty (within reason). Just be aware that, once you do start the bounty:
- You can only award it in the next 7 days
- You cannot cancel your bounty, so if you didn't get the answer you were hoping for — tough.
- The bounty will be automatically awarded if you don't award it yourself
- The answer must have been given after the bounty was started
- The answer must have a score of at least +2
- The answer must not have been written by the bounty starter
- The answer will only receive half the bounty
- Your next bounty on the next question will have to be for more reputation than this bounty (or 500 reputation)