Generally I am comfortable with injecting non-DTV signals and breaking them back out of the satellite feeds by using combiners & diplexers.

Does this practice apply when using the SWM systems and if so is there any specific parts I should be using to do this?

I commonly do this with various radio signals as well as CATV signals when I can't easily run a new wire that is dedicated.

For the instance I am working on right now, I am installing a Wi-Ex ZBoost PCS/Cell phone amplifier and am trying to avoid having to retrofit repeater antennas in this 3 story home.