Hence why I stated "It should take about 2hrs but without more information I can't give you an accurate amount of time". 

Obviouly any smart company would do this job for T&M, the OP wanted an estimated time to complete this so I gave him one.  From my understanding he is asking for someone to remove a VCR ir driver and replace it with a DVD ir driver.  This may also entail altering/adding a couple buttons on the ML-600 remote, as well as maybe having to alter the stepper to change the amp to a different input.  If you/your programmer can't perform the above within 2hrs you have some major time problems.  To be clear I am assuming that the DVD player is a well know brand so learning commands isn't required, and the system is a one room system with a DVD, amp, sat box, and TV.  Like I said to the OP, without having the program and knowing the DVD player brand providing an accurate time isn't possible.