I assume you mean icons from "Stardock Design" (SD)?
1. email SD and ask permission.
2. Just modify them and use for yourself: not publishing nor sharing them.
3. Ask a Moderator to take a look at them and see what they think.
The polite thing to do would be to email Stardock Design (keep a copy of the email) and offer to send them what you're doing and ask permission to publish (if that's your intent).
Oh yeah...wait for the answer. They're good people, but busy and it might take a little time for the answer.