Welcome, acidburn!
"Hydrocarbon" is too vague! If you start from Diesel oil, which is essentially a hydrocarbon, then making Diesel oil of it is trivial. So what is your starting material? Bigger molecules than Diesel oil, or smaller? With multiple bonds from the beginning?
Then, cost. Diesel oil is badly cheap, with some 80% of the consumer price being taxes, depending on the country. Do you plan to be as cheap? How cheap is your feedstock? How huge shall your production be?
For instance, I'd be happy if the C3+C4 fractions of oil and gas were transformed into useful compounds. Presently they're burnt at the well because they sell for less money than their transport would cost - which would only need a boat with pressure vessels.
Many groups also conduct research on obtaining car fuels from used tyres. Hevea sap (the precursor of latex and natural rubber) gives similar molecules, but probably more expensive than oil.
Converting coal into liquid fuels has been done too, mainly in times of shortage. Wood and charcoal too. Turpentine is a potential source as well. But in normal times, oil is just too cheap.
Palm oil is nicely cheap. Not a hydrocarbon, but already transformed into bio-Diesel. Almost the same with cane alcohol.
Processes exist for all these transformations, some known for decades, others being still investigated. It's not one single process for all sources. Also expect a complicated plant with many recycling loops.