According to the ATEC Scoring Guide the run may be either earned or unearned, subject to the standard guidelines for scoring earned runs. But an exception is made in that if the run is earned, it is credited as an earned run against the TEAM, not the pitcher and thus does not affect the pitcher's earned run average. Any subsequent earned runs scored by runners other than the one placed at second are attributed to the pitcher.
This agrees with the scoring rules in section 11 of the ASA rule book.
Check out page 65 at this link for details on scoring runs in the International Tiebreaker:
ATEC Scoring Guide