1. A method for inserting one or more instructions into memory-resident machine code stored in the memory of a computer, the method comprising: preparing, by a program-controlled processor of the computer, a block description of the one or more instructions, the description including, for each instruction of the one or more instructions, an instruction description including a constant-portion value and descriptions of each variable portion, wherein the descriptions for each variable portion further includes a supplied variable-portion value and a shift value for shifting the supplied variable-portion value; for each instruction description in the block description, building, by the program-controlled processor of the computer, a memory-resident instruction from the constant-portion value and descriptions of each variable portion; and inserting the memory-resident instruction into the memory-resident machine code.