It's not that simple man. If you just stress the fuck out of a plant and make it go hermie, you will end up with offspring that are mostly complete hermaphrodites. The way that seed companies do it, usually, is to have a bunch of different females, hundreds of them, usually hooked up to a hydro setup (its way easier to do with hydro), and then just start stressing them a little at a time. As individual plants turn hermaphrodite, they are removed or killed. The stress on the roots is slowly turned up over time, and eventually almost all the plants will have turned hermaphrodite. It is then that they take the plants which showed the MOST resistance to turning hermaphrodite and are still totally female, and they stress the fuck out of those plants, because their genetics are less likely to produce hermaphrodites since they have a strong genetic resistance to it. Eventually, even these plants will (hopefully) turn hermie, and then they are used to pollinate other plants that showed the same level of resistance. You need almost unlimited resources to do this correctly, from what I gather.
If you just have a few plants in some soil, you probably won't have the genetic diversity needed to find the truly resistant plants. I mean, if you just use the pollen of the FIRST plant that goes hermaphrodite, you are actually INCREASING the chance that the next generation will grow into full hermie plants. I don't mean just a couple male flowers either. Half or more of the "buds" will be male, and will pollinate every female bud you have to the max! That means your buds would literally be 50% seed, dried weight. You don't want that, do you?
The process of feminization is very complex and scientific, from what I understand. You would end up with alot of hermaphrodite seeds if you did this. I could be mis-informed, however. Personally, I wouldn't waste the plants. This is something best left to the pro's, I wouldn't attempt it. Even trying to figure out how much of the acid to add, and when to add it, would take alot of computations. Also, it doesn't sound like you have several hundred plants around, which is about how many you would need to do this. Seriously, I would just try to make regular seeds. That is something you can do pretty easily, and then you can just take clones off your mother plants and have a nearly unlimited supply of females for your garden. Just trying to warn ya, I don't think it's worth it. Not trying to be a jerk or anything, just don't want you to waste good seeds or good smokeable bud.