I have not heard of such efforts, and there are two reasons why i don't think they're necessary.

1) The chance that life could arise on an asteroid seems impossibly small. The chance that an alien civilization has visited our solar system and left artifacts on an asteroid are equally remote. It's not remotely likely enough to be worth investing time in working up a protocol.

2) If miners on Earth discover archeological artifacts, they have financial reasons to cover it up, as reporting the find does not benefit them, and will only cause them headaches. If asteroid miners discovered alien artifacts, however, there is no benefit to covering it up. It would be the biggest discovery in human history, and those artifacts would be immensely more valuable than any ore they could possible be seeking.