Ask HN: Termsheet for advisors?

So I'm thinking of persuading a couple of smart folks to act as advisors for my startup. In return for their smarts and support, I want to offer them about 1% equity vested over 2 years.

How do I go about it legally?

Is there a sample contract that I can look at? There are a lot of termsheet samples at angel level that folks can use if someone is offering money. But I couldn't find a lot of information on getting advisors on board... so any help would be appreciated.

Thanks!