I got my hands on a PSU 0-10V Resistance dimmable version for LED which have a dimming function called current-sink type control.

What properties does the signal need to have into this? what happens if I just put in say 5VDC from another PSU into the 2x dimming cables?

 

I got my hands on a PSU 0-10V Resistance dimmable version for LED which have a dimming function called current-sink type control.

What properties does the signal need to have into this? what happens if I just put in say 5VDC from another PSU into the 2x dimming cables?

That's not much information to work with. Do you have the model and make of the power supply? Do you have an instruction manual or spec sheet for it?
The chances are that if you connected a 5VDC source to the control input terminals, you would see smoke from both supplies.
You mention "Resistance dimmable" and "current-sink type control" which would suggest that a variable resistor between the terminals would control the output but the value of resistor is anybody's guess.