Thanks for the reply Litjan and sorry for the delay in getting back to you. I am in New Zealand and it is 12.10 pm here. Your post was received while I was tucked up in bed last night.
After lots of trial and error this is what I have been able to sort out regarding moving the speedbrake lever using Saitek throttle levers / switches.
Allocate "Speedbrakes extend one" to a lever or switch and "Speedbrakes retract one" to another lever or switch.
One click of the "Speedbrake extend one" lever / switch will move the speedbrake lever from "Down" to "Arm".
To move the speedbrake lever from "Arm" to "Flight Detent" the lever must be moved slightly towards the "Flight Detent" position using the curser, when you require the speedbrakes to be deployed to the "Flight Detent" position click the allocated "Speedbrakes extend one" lever / switch, a second click on the lever / switch will move the lever to the "Up" position.
To move the speedbrake lever from the "Up" position to the "Flight Detent" position click the allocated "Speedbrakes retract one" lever / switch. To move the lever from the "Flight Detent" position back to "Arm" first move the lever slightly towards the "Arm" position using the curser. Now the lever / switch can be used to move the lever back to "Arm" then "Down" with the second click
Cheers
Graeme