I don't know if it works on autos the way it works on photoperiod plants, but if you keep temps low during the first week after germination (65-70 F) and have a source of ethylene in your tent, the male/female ratio leans more toward females.
This was info passed on to me that I tried and it seems to always work for me. It may be "bro-science" or an old wive's tale (cool old wife), but I've been keeping the stats for the seed runs where I've done it and I've been on the 50%+ side each time, so far.
The ethylene source can be a ripe banana or an apple, depending on the size of the space.