1911 disassembly SA question

I have a field manual (dept.of the army) and the manual go threw it step by step also found another set of instruction on the net someone sent me and the only problem between the two are : The thumb safety?
The military manual say:remove the safety lock then the mainspring housing.
The other set of instruction state remove the mainspring housing first(but you must keep the grip safety pressed all the time)Then re cock the hammer and remove the thumb safety and then the grip safety:except for this part the rest of the instruction remain the same.
Any ideas on the above to clear things up

I was over at there web site seem they stop on the take down when it gets to the ILS in the MSH
Question if you leave that ILS alone and still keep it in the firing position is here anything special that has to be done to the MSH ?
I read it:seem more on locking the trigger when not in use :when the pin is removed any thing special has to be done or continue with the dis assembly with the instruction from the field manual