Forcing moves is one of the hardest things to accomplish in route setting.
In general, setting easy routes is easy, setting hard routes is even easier, but setting beta specific intermediate routes can be next to impossible.
One of the most effective methods I've found for establishing interesting problems that force specific beta is to play take-away. To play, designate your starting hold and your end hold, then get bunch of guys to climb with. At the beginning everyone is climbing open holds, but each time someone climbs, they get to choose one hold to take away from the problem, and no one is allowed to use that hold anymore. Every time the problem is climbed it gets more and more challenging, and the beta gets more and more specific. This method of problem setting helps eliminate those alternate solutions to a problem, because if you notice a bunch of people all using the same hold to get through a part, you can take it away and force them to do something different.
Something I'd do to force moves, was to place holds so they could only be held in one very specific position. Such as using slopers on an overhang, people can't hang from slopers from specific angles, so they're forced to think more about body position and footwork. Avoid using too many jugs when setting problems, because stronger climbers can just campus through them, swing their bodies around, or dyno to the next jug, etc.
One of my favorite things to do was put jugs on the wall in a way that made them anything but juggy to hang onto, like putting them on upside down or backwards. This forces people to think about the hold differently, and use it as a sloper, undercling, gaston or crimp. People tend to get too familiar with climbing holds, for example, if I see a teknik fatty-fat pinch in a route, I know exactly what I'm in for. But from the right angle, that fatty fat can transform from a fat pinch to a dirty sloper. Use a hold differently than it's normally used and you can change the dynamic of the problem.
One dirty trick you can play on people is stick a really juicy jug in the problem that distracts them from the proper solution the to the problem.
There's nothing really systematic about route setting. It's more of an art than an exact science. You need imagination, or you need inspiration. Watch some bouldering competions online, or better yet, go participate in a competition. Climbing a variety of problems helps you bring a greater variety of potential problems back to your gym. Climbing outdoors gives you a lot of inspiration too. It's common for people to duplicate the crux of their latest project so the can practice it in the gym, then go flash it on the boulder.