a. make sure the four genes are on different chromosome
b. plan the breeding carefully so that for each round of breeding the
mendelian ratio of getting your target genotype is no less than 1:4 ( below
1:16 is almost mission impossible). This way, in general, it takes one round
of breeding to introduce one mutated allele to the genome. Say you are
planning to introduce 4 mutated genes, 2 homozygous 2 heterozygous, you will
need 4 + 2 = 6 round of breeding. Each round will take at least 9 weeks (