The hint for this is in the release video.

Go to Child Lane using the platform selector menu
Find the phone and dial 36133
Listen and then head to the clock
Turn it to 2:40 and take the train

Talk to the janitor, he wants coffee
Grab the coffee filter from his pocket
Turn around until you find a box, grab the coffee and cup from it
Go to the coffee machine and take the pot
Head to the nearby washroom and flush the toilet
While the toilet is full of water grab it with the coffee pot
Go back to the coffee machine and add all the bits:

• coffee pot with water
  
• coffee filter
  
• then coffee

Run the machine to get coffee
Head back to the janitor and give him the cup, then the coffee
He will drink it and run to the washroom
Grab his mop
Go to the washroom and grab the key from the janitors apron
Use it on the research lab door and we're in!

Once you enter there is a fuse panel to the room to the left.

You have to move the fuse around to unlock doors.

The map is oriented on its side so it's a bit easy to get confused so here is an edited map for reference.

At the fuse panel, put the fuse in the top slot
Leave the room, then go straight and through the nearly opened door on the left
Grab the glass from the ground and then look at the vent
Stop the spinning fan with the mop and grab the fuse inside
Take the mop with you
Head back to the fuse panel and put fuses in slot 2 and 3
Leave the room, head straight through the door and follow the path to the open storage room
On the ground is the cipher for the container on the top shelf

Open the container on the top shelf for a keycard
Grab the wheel from the box on the bottom shelf before you leave
Leave the storage room and turn left into the room with a prisoner
He wants out so let's put that wheel on the wall next to him and spin it to release him
There is a dead mouse on the ground next to him, poke it to get a kidney
Backtrack to the fuse panel room
Put a fuse into the 4th and 6th slot
Leave the room and head right through the open door
Follow the path and first ignore the flask sign and go straight
In here is another vent, look inside and grab the matches
Leave the room and go to the left, this time following the flask sign
Put the keycard in the slot next to the door and enter
Check the desk drawers for toilet paper and a floppy disc
Put the kidney on the tray on the desk and the coffee pot on the desk
Backtrack entirely out of the research lab and go back to the washroom
Give the toilet paper to the janitor and back away
Go back and now the washroom is clear again
Flush the toilet and grab water with the glass
Return to the research lab and back to the room we opened with the keycard
The instructions for this are on the floor

Use the matches to light the burner and heat the water glass
Then pour the coffee, then boiling water, then acid onto the kidney
The kidney will turn into a weird goop creature - poke it and it will jump off the table
Continue to use the mop to poke it and detour to the fuse panel room
Place a fuse in the 1st slot and continue following the goop to the room with the fan vent
It will jump to its death by spinning fan and gooooop everywhere
Go into the vent and grab a 3rd fuse at the back
Backtrack to the fuse panel room and insert the fuse
Put it in the 5th slot (so you should have 4,5,6 in)
Leave the room and head right and follow the path to the cube door to see the janitor is in here, totally safe and sound
Go left and talk to Rose
Rose will enter the machine, push the grey button and then the red button
Take the black cube from Rose
Head back to say hi to our janitor friend and ohhh noo... I'm sure he's fine
Follow the trail of blood back to the prison and talk to Rose
Turn the wheel again to close the cell
Take the key from Rose
Follow the blood back to the door with the cube above it and insert the key
Enter the room and see a cool Past Within device
Turn the device on with the switch at the bottom right and the red switch
Put the black cube above the device and then insert the floppy disc to complete the update!
You will get Run, Harvey, Run achievement.

There is a secret message to be used in The Past Within if you own it (you should totally buy it)
1935

If you want to leave the area, backtrack towards the entrance and you will see 3:45 written on the chalkboard on the way out

Set the clock on the platform to that time and you will return to child lane

I don't think the lab shows up on the platform selector, you'll probably have to set the time back to 2:40 to come back

Thanks RifleIsAHoliday for updating these details.

Where to use secret message in the different game The Past Within:
1. Start new Past Within game in the Future Mode
2. Switch on the Device
3. Enter 1935 as a year, put tumblers into the following positions: up down down (top row) and up down up (low row), move switches in the following positions: second(top), fourth(middle), fifth(lowest)
4. Receive green floppy from the Device
5. Fut the floppy into the floppy driver right under the display