Yum doesn't have a way to do this. It would counter the purpose of the package manager.
Moreover, it will usually render a package dysfunctional. 
Package maintainer's put effort into ensuring dependencies are properly defined and not overly restrictive. That said, you can install the rpm with the rpm utility using the --nodeps flag. As a result, it becomes your responsibility to manually manage the package's life cycle.
In theory, it should be possible for someone to write a tweak (stand alone, definitely.built into Cydia, maybe) that reads these package files and parses the package name, tweak name, version, dependencies, etc. The method suggested by gameking30578. In terminal type: apt-cache showpkg com.package.name. Does just that.
Although this is generally unwise, you may find it useful to experiment with this option. The syntax is: rpm -i --nodeps [package].rpm Yum's statement on the matter:.