Flags are between 0x1 and 0x3FFF. Anything after is variables. So make the person, use hidesprite and the person event number and set a flag which is the person ID. 0x1000 and after are flags that you should use.
Thanks alot! So it is normal that my person only disappears once the player begins to move (after I've run the setflag [peopleid] script), and therefore I have to use hidesprite. Right? Anyway, I think I understand! :p