MySQL Replication: Slave with Different Column From Master
WOW, I remember your last question !!!

If you kept the s_relations_old on the slave, just switch back and start replication.

STOP SLAVE;
ALTER TABLE s_relations RENAME s_relations_bad;
ALTER TABLE s_relations_old RENAME s_relations;
START SLAVE;


You should perform the conversion of the temp_col on the master so that you let that ALTER TABLE replicate to the slave.

You will have to bite the bullet on this one and have some downtime.