Yes you can do it that way. Make sure you follow the steps precisely and make sure you have the latest one. 1.3 or something.
I honestly stopped using my Saitek throttle quads earlier today. And I stopped using the reverser buttons on them years ago as I found them just to sloppy and always triggering just from taxiing. So what I did was setup one button on my joystick to enable that plugin and then ran the throttles up. If you wish todo it that way it is not described in the readme but its easy todo. Select the button you want to use in the Button assignment table. Select for FS Action. Scroll down to LuaToggle ThrottleManager. Make sure you select the Toggle one. There are like 9-10 options. Set it to parameter 1 click okay and exit FlightSim. Open up FSUIPC.ini and find the entry that looks like this.
54=PA,8,CL3:T,1 -{LuaToggle ThrottleManager}- the ,1 at the end is the parameter.
Copy paste that line 2 more times and change the parameter to 2 and then 3. The parameter assigns the engine. Should look something like this when your done.
54=PA,8,CL3:T,1 -{LuaToggle ThrottleManager}-
55=PA,8,CL3:T,2 -{LuaToggle ThrottleManager}-
56=PA,8,CL3:T,3 -{LuaToggle ThrottleManager}-
Open fs. Press that button you should hear a ding. If you don't something isn't setup right. All done. I have it setup on my 777, ifly 747, pmdg 747, md-11 and works fine on all of them and more convienent than a seperate axis for the reverser. Now you should be able to setup a spoiler axis and a flap axis on your quadrants. since you freed up 3 axis assignments.