Some facts

• Only 43 states allow write-in candidates, so that's access to 494 electoral votes.
• In these states - Alabama, Delaware, Iowa, New Hampshire, New Jersey, Oregon, Vermont and Wyoming, write-in candidates do not need to be registered; voter can virtually vote for anyone they like.

How are Elector College electors chosen for write-in votes for President?

According to the State of Maine Gov Write-in Candidate Requirements, a write-in candidate is required to name his/her 4 electors during registration. (Maine has 4 electoral votes)

A presidential write-in candidate must name the candidate’s four electors when the Declaration of Write-in Candidacy is submitted.

So, basically, they are chosen by the candidate himself/herself.

If not, does that mean that write-in candidates can never receive electoral votes, despite what ballots say?

They can receive electoral votes in states that allows write-in candidates. However it has never happened, so I don't think that the process is super clear in all states. Only some specified the process in registration forms. Write-in candidates don't really have a large chance of winning any state in the first place.

Say that miraculously a write-in candidate got 51% of the vote. Would an elector for them be chosen after the vote?

This article does have a hypothetical example at the end, quite interesting to check it out since the example surely would be better than I coming up with one.

Some facts

• Only 43 states allow write-in candidates, so that's access to 494 electoral votes.
• In these states - Alabama, Delaware, Iowa, New Hampshire, New Jersey, Oregon, Vermont and Wyoming, write-in candidates do not need to be registered; voter can virtually vote for anyone they like.

How are Elector College electors chosen for write-in votes for President?

According to the State of Maine Gov Write-in Candidate Requirements, a write-in candidate is required to name his/her 4 electors during registration. (Maine has 4 electoral votes)

A presidential write-in candidate must name the candidate’s four electors when the Declaration of Write-in Candidacy is submitted.

So, in Maine, they are chosen by the candidate himself/herself.

For other states, some have clear guidelines, while others aren't that clear. You may want to check out this article for elaboration.

If not, does that mean that write-in candidates can never receive electoral votes, despite what ballots say?

They can receive electoral votes in states that allows write-in candidates. However it has never happened, so I don't think that the process is super clear in all states. Only some specified the process in registration forms. Write-in candidates don't really have a large chance of winning any state in the first place.

Say that miraculously a write-in candidate got 51% of the vote. Would an elector for them be chosen after the vote?

This article does have a hypothetical example at the end, quite interesting to check it out since the example surely would be better than I coming up with one.