I once used a BMX stem as a make shift plastic hose clamp thingy, I just clamped the hose close to the bolts and tightened the top of the stem on to it... not the best set-up in the world but it worked. But yeah, heat the tube with boiling water and tap the barbed bolt in `straight` with a hammer. If you get the first lip of the bolt in, just heat both some more and keep going.