I think the key is figuring out the 'right' amount of heat without weakening the hose.
Well, while I can see the need (looking myself for a solution as many pre-shaped ST1100 hoses are unavailable by now), I'm not fully convinced...
After all have the hoses/lines already been vulcanized (the sulfur molecules bond/replace rubber-chains at 120~160°C/250~320°F), which is why they always want to pop back into that circular shape of the spool they've been stored/delivered on...
Not sure if this bond can so easily be broken and reshaped again, or at what temperature range... (imagine your tires would loose the molecular bond...)
a) I see that Honda pre-curved hoses mostly made of their two-color/layer material (grey out-/black inside), so maybe those lines actually support heat-forming?
b) to ensure a more precise and evenly heat (ideal temperature TBA), I'll use a stove and build a jig (like wiring the thing in the intended bend/shape onto a metal grille)...
c) for larger diameters the mentioned
Unicoil adapters seem really safe...
I do see an imminent need for items like the ST's carb bowl drains (connecting to the 4-way T)... hence looking for a reliable solution myself...