Er, well, I'm not much of a hardware guy. But there's nothing special involved in consumer IR signals, beyond just turning the LED on and off. I suppose the hardest part of the IR signal to accurately replicate would have to be the carrier frequency; while each individual on/off command will last for something like 500 to 1000 microseconds, during the time it is set to be "on", the carrier frequency will further subdivide it into smaller on/off pulses at a rate of something like 20 to 30 microseconds. (There's even a "duty cycle" value that specifies how long the LED should be left on during each carrier pulse.)

So, I guess it's a question of how well the hardware can keep up with these pulses. Most IR receivers are tolerant of some sloppiness in the timing, but yeah, get too far off and it just won't understand what you're trying to send...