The assembly instructions from arcol.hu are ready on his wiki
Assembling the Arcol.hu 4.0 Hotend
The beginning of the assembly is very well described in the arcol.hu wiki for the 3.0 hot-end and it is the same for the 4.0 hotend.
Follow this description until you get to this step:
The next step is to insert the short PTFE-tube inside the heatsink block like this:
You should also take a look at the thread inside the heatsink and remove any residues which might be left from manufacuring. Those could block the nozzle later.
Then you screw the stainless steel connection tube inside the heatsink block.
At the other side insert the grub screw to secure the PTFE-tube inside.
Use a screwdriver to make sure the grubscrew sits tight.
Then you can fix the whole construct inside the slot of the wooden extruder connection.
The wood is 5 mm thick. The slot inside the heatsink is a little bit smaller (4.7 mm) so that one has to use pliers or a vice to fix the heatsink inside. This ensures a firm grip of the hotend.
The filament hole has to be in one row with the connection holes in the wood-clamp.
Finally you screw the previous assembled nozzle/heater/thermistor-block onto the heatsink and put thermoresistant isolation around the wiring of the hotend.
Be sure the hotend is screwed on tight or else the hot-end will block or leak plastic. The steel-bolt has to cut the winding into the bottom of the nozzle.
You should use a wrench or pliers to be sure it is firmly mounted.
It looks like this, if it is too loose:
The two holes on top of the woodplate have a distance of 50 mm. This fits exactly into the holes of the wades extruder used to connect it to the x-carriage.
You can insert the inlay and clamp the Wades extruder onto the hot-end or widen the hole for the inlay until you can put the upper part of the heatsink into the extruder.
After this you can now connect the wires with the plug as described at the end of the arcol 3.0 assembly.