i think in order for them to succesfully graft, the plants need to be of the same genus or species
if you are looking to make your tomatoes into rasta tomatoes, you are gonna need some atomic microscopes,needles and high powered genetic engineering equipment and possibly a detailed genome map of the plants you are gonna be working with
You have to get the pollen from a male of the strain of your choice. Then pollinate a female strand of your choice. Thats the easy summary, i am no expert so read this link. Its RUI's grow FAQ, very helpful
Just get a male and and a female plant --bag the male and than cover a lower female branch (bud) with male in bag (or branch of male with flowers on it )and make beanie babies, than the strains will surely combine.