Looks a litle bit too close to impossible
it would be better if that jet plate was split into 2, one for the cavity and one with holes straight down otherwize its probably just gonna pour out of there very slowly.
Just remember that you want a concentrated cooling spot right over the core and dont need anything way the heck out there.(not much farther than 1" diameter)
Im gonna say from my experience, impossible on manual machine and at least 10hrs on cnc machines.
How are you liking alibre? I tried it out for about a day when I didnt know how to run it, I should take a look at it again. It might be hard going backwards from pro/e and solidworks that I am being taught here at college
Jon