I think it would be difficult,as we don't know how to select for the desired path. The preliminary steps that led to the essential traits later might be due to selection pressures for effects we don't know about. Just breeding for some general intelligence test result might lead to a dead end.
If the breeders did know, how long would it take the needed mutations to arise? That depends on population size. So, orders of magnitude difference depending on the size of the operation!
How many individual mutations are needed? You have the probability of one occuring, then you detect it and select it, but it still needs to spread over the population which takes many generations.