How do you fit an external switch to a Grundfos 15/50 pump?

How do you fit an external switch to control the variable speed on a Grundfos central heating pump fitted to a Worcester 15/50 central heating combi boiler? The higher speed is required when hot water is demanded however the lower and much quieter speed is ideal for the domestic heating. The proposal is that the pump switch would be located outside of the boiler cupboard connected by a heat resistant wire to the pump. My mistake when originally installing the boiler was to locate it in a cupboard close to the bedroom. The whir of the pump disturbs my wife's sleep when set at the higher speed!