Ehm I am pretty sure you can. Atleast I tried that back when BC replaced the hopper(the item which is now the Chute). So if it doesn't work with the Hopper, try the Chute(Chute cant pull items from inventory above though).I would test this myself but I'm don't have MC on this machine... very simple question!
Can a buildcraft pipe shove items into the side of a Hopper? If you have tested this, please let me know if it works, I am scheming in my head and I must know right meow!