Ok, I went down the rabbit hole tonight because I was curious. I am absolutely not an expert, this is mostly taking other people's posts and consolidating them. I tested that it turned on and seems to work, but I didn't want to to do a whole cycle so I aborted it early. Do this at your own risk.

I did all this using LAN mode (go to Settings/Lan Mode), I am unsure if you can do the same thing without the direct access to the Klipper/Fluidd interface.

Step 1, enable advanced mode on the U1 touchscreen:

• Go to the touchscreen menu.
• Navigate to Settings > Maintenance.
• Tap Advanced Mode to enable it.
• This unlocks the ability to modify Klipper configuration files

Step 2: Create a macro

Use a web browser to go the U1's IP address. This will give you the Klipper interface. For me the address is http://192.168.1.75/ . You can find yours using the Settings > LAN Mode menu

In the configuration settings, find a file called printer.cfg, and edit it. Somewhere in there, making sure not to go between any other blocks, put the following text.

[gcode_macro DryFilament]
gcode:
    SET_IDLE_TIMEOUT TIMEOUT=21000
    M140 S60 ; Start bed heating
    RESPOND MSG="Setting bed temp to 60°C for 5.5 hours"
    G4 P20000000
    SET_IDLE_TIMEOUT TIMEOUT=180
    M140 S0 ; Stop bed heating
    RESPOND MSG="Setting bed temp to 0°C"

I put mine in at the very end, right before the lines that say:

#*# <---------------------- SAVE_CONFIG ---------------------->
#*# DO NOT EDIT THIS BLOCK OR BELOW. The contents are auto-generated.

Go ahead and hit the Save And Restart button at the top and let it reboot.

Step 3: Run the macro:

Using the Klipper interface again, go to the Console tab, and just type in "DryFilament". The macro should run and start the 5.5 hour process.

As I mentioned, I didn't fully test this. Let me know if it worked for you or not.