Recently, I had to clean up my main computer after an upgrade from F17->F19 hung and had similar issues. I spent some time on #yum and got help with various issues, but from all I can tell, there isn't a --force flag for yum, and none of the devs seems to think it's a good idea to have it. Have you tried this:

package-cleanup --problems

This will give you a list of every current conflict. If you have more than one, it may be that they're all related to one package, and if so, you can concentrate on getting them all fixed at once. Even if they're not, they'll tell you what needs to be done, although it may turn out that there's a conflict you can't clear because it's looking for a package that doesn't exist. As an example, system-config-network is complaining that python-iwlib is > 1.3, but the only version available is python-iwlib-1.2-1.fc17.i686, so there's no way to resolve the conflict.