The original LiteOn hacks were using a checksum balancing method of hacking. This worked great for recorders where the checksum bits were known. Like you say, newer firmware codes changed these locations and made it hard to hack the newer firmware, but they were figued out.
The Smart Updater uses a bit balancing method that allows the hacks without needing the checksum location. This came from the need to hack the ILO recorders, since the checksums were not known.
For Macrovision and 3-hour mode, the same code strings as the LiteOns were present in the firmware but the checksums to balance the hacks were not known. So to make it work this is what was done:
Macrovision: The code string for the Macrvision hack also included the bit for the region code. To make it work, the Macrovision bit was changed +1 and the region bit was changed -1 to balance it. So basically, in one shot, this disabled Macrovision AND made the recorder region free, assuming it was a region 1 recorder. For anyone with a recorder other than region 1, you just use the 2960 remote hack to change the recorder back to the region you needed.
3-Hour LP Mode: To offset the +4 change needed in the 3-hour mode hack, there was a filler bit in the same area as the 3-hour code string that was changed -4 to balance the change.
As you can see, this method of hack makes it applyable to most any LiteOn/ILO firmware since the checksums are not needed.
There have been some exceptions and the Smart Updater is being changed as they come to light.
Thanks goes to Mr. Wizard at the Techolio forums for the program!!!