To do it the right way, you'll need:
Table vise
Hammer
14 gauge spoke with nipple threaded upside down
Lube of some kind
Piece of wood block
1. Take the piece of block, drill a hole slightly smaller than the diameter of the hose. Cut the block in half so you now have a clamping device for the hose
2. Clamp the hose with 1" or so exposed at the top
3. Take the 14 gauge spoke, cut to 4" or so and thread the nipple upside down
4. Lube the tip of the barbed fitting
5. Insert the spoke with the nipple through the barbed fitting so now you have the upside down nipple sitting on top of the barbed fitting (threaded side)
6. Gently tap the head (nipple) and keeping the spoke/barbed fitting/hose straight
Now you 'can' do this without the table vise and the piece of block, the spoke/nipple method will keep the barbed fitting fairly straight. Just make sure to lube and tap slowly.