1. A method for dynamic insertion of one or more program instructions, for inserted code processing ( 191 , 1910 ), by a first computer task, termed manager task ( 29 ), in a second computer task, termed target task ( 21 ), executed in a memory address space managed by a system software in a computer system, comprising: storing, within a memory area ( 210 ) outside the memory address space of the target task ( 21 ), of at least one hooking datum ( 211 ) representing initiation data for the code processing ( 191 ) to be inserted; executing, within the execution of a system routine (r 1 ) called or controlled by the target task ( 21 ), an instruction (h 1 ) termed hooking which initiates a test of the hooking datum ( 211 ) executing the inserted code ( 191 ), according to the result of said test and instead of the program instruction (I n+1) following the hooking instruction (h 1 ) in the execution of said system routine (r 1 ).