I brought Bella & Milo home at 6 weeks and they cried at first too.We just put a hot water bottle in bed with them and they were fine after that.I´ve never heard of a 6 week old puppy needing to be fed every 4 hours though,and all of my 5 babies were brought home at 6 weeks old and they were completly fine.
By that time,even the mother isnt feeding them that often (if she even still is).At 6 weeks old,Milo & Bella hadent fed from their mother for almost a week,which is why we were able to bring them home (the same goes for my previous 3).
We DID leave their (wet) kibble down 24/7 for the first week just to make sure they had round the clock acces to food and water,but that was all.
They just tend to cry and sometimes ALOT at first,but it soon passes
Edited to add:Milo & Bella are now 2 months old (on the 21st) and we feed them 3 times a day.Regular dry kibble (RC yorkshire terrier)