Ansys Workbench picks elements for you, so you can't implicitly control element types, keyopts, or real constants. Instead, you choose attributes.
I have to say, if you have the opportunity to upgrade, Ansys WB 13 is leaps and bounds better than Ansys WB 11 when it comes to meshing. Ansys Classic can mesh pretty much anything under the sun with enough effort.
In Workbench, you can control element size, meshing method, and so forth by inserting mesh controls. You'll likely have to slice up the model in DesignModeler and create multibody parts (Freeze Bodies>Use "Slice">Select Parts>Right Click>Create New Part).
It takes a bit of a knack. People who'd been using Classic for a while found WB11 pretty frustrating; if you're good with Classic it seems crippled. Still, it's not bad, and it can get you to an acceptable mesh.
Again, Ansys WB 13 has far better meshing tools, and the ability to mesh bits of the model at a time, rather than asking the mesher to figure out the whole thing. It's worth the upgrade. If you can't upgrade, and WB isn't getting you the mesh you want, try flipping over to Classic.
