I've read many articles on various techniques for converting colour to black and white or sepia in PSE, but I haven't been able to find a good method for creating two tone effects. In fact some say it's just not possible in PSE.
So, as I never take 'not possible' as an answer, here is my method.
First of all you need to select your photo and convert to black and white, using a method that does not destroy the tonal data.
In PSE, I find using the two Hue/saturation layer method good and effective but there are others if you do a bit of research. Also careful selection of the photo will help, choosing one with strong highlights and shadows if possible.
Once you are happy with your black and white photo, we are ready to begin the process. It's always a good start to duplicate your background and name it Base or whatever you like.
Next, you need to separate out the highlights and shadows. In the layers pallet, open up 'create new fill or adjustment layer' and select Threshold. Your picture will change to black or white and the adjustment slider will open up. Use the slider to alter the image until you are happy with the black/white separation. The black will become one hue and the white the second so it's good to have some idea in your mind, what colours you are aiming for, but not essential at this stage.
In my example, I wanted the highlights to be more prominent so I moved the slider to a value of 52. When you are happy, click ok.
The next step is to create two hue/saturation adjustment layers with the black/white image, you have just created, as a mask. One mask being the inverse to the other.
Select the magic wand tool. Check that the tolerance is 100% and most important the contiguous box is unchecked. This is so you pick up all of the white or black with one click.
Now select all the white by clicking anywhere over a white area on your image. You should get the marching ants. It is also a good idea to add some feathering to your selection, which helps to blend the colours. Use Select > Feather then make the feather radius around 15 pixels.
With this selection made, open up 'create new fill or adjustment layer' and select hue/saturation. You should now see a layer with a mask looking remarkably like your image. For now click ok and rename this adjustment layer as Highlights.
Now use the magic wand again, this time selecting the black. Feather the selection again and then create another hue/saturation adjustment layer. Click ok and name this Shadows. All you have to do now is make adjustments to the Highlight and Shadow hues.
First switch off the Threshold layer and then open the Highlights adjustment layer. Check the colourize box and then adjust the hue slider until you have your colour choice. You will probably need to adjust the saturation level as well. When you are happy, click ok. Now repeat for the Shadows adjustment layer. Don't forget to check the colourize box.
I completed this image, adjusting curves, levels and crop.