In Babe Ruth's last season or two, he had a courtesy runner run out his HR's, which was legal back then. He'd touch first, then go have a smoke while the PR would complete the circuit.
In slow (and fat white guy) pitch in some leagues, you are forbidden from running them out. lik was said, she "earned" her homer.
In MLB rules you don't earn a homerun, however, until all four bases are touched. BUT, they have a rule that specifically addresses a player getting hurt while running out a homer. Rule 5.10 (c)(1) allows the ump to call time and allow a pinch runner.http://mlb.mlb.com/mlb/downloads/y2011/Official_Baseball_Rules.pdf
3 or 4 years ago, Benjie Molina hit one off the tin roof at ATT Park with a man on and it bounched onto the field. Umps didn't signal it a HR cause they thought it merelt hit the wall so Molina stops at first. His manager puts in a pinch runner. When the pitcher tossed the ball to the ump for a new one, it was noticd there was green paint on the ball, so umps did replay and awarded a homer. Ump told the pinch runner to run it out so he did.
I don't know how they scored it but I guess Molina got both RBI's but maybe didn't get the run scored.