How to specify some weight of ANN?

Is there a way to specify some weights of ANN, as I build a parallel ANN structure, and the output of the whole ANN is the summary of sub-ANN, say Out=Out1+Out2-Out3,so the weight of the output neuron are 1,1,-1. My question is: can I specify these three weights, while the other weights will be updated automatically?

Answer 1

[Greg Heath]

Set the learning rates of the output layer to zero.

[liang]

That sounds make sense, but I do not find how to set the lr of the output layer to zero.