Usually just find a spare socket to plug it into. Difficult bit is getting the plumbing right - read all the information supplied with the pump or look on the web before you buy it.
In the uk the best place to fit a power pump is in the cupboard with the emersion heater. Simply fit another spur fed from the existing one the conections are the same as a 3pin plug brown =live blue=neutral and green/yellow=earth the pump has an internal switch that only operates when you turn on the shower
They have a wiring diagram in them when you bye one. Don't forget to have a GFI and turn off the power before wiring.
