Ah, I misread your post. But the answer is still the same: you'll need to collect both the immobilizer value, and the "immobilizer hex" value referred to in the instructions for switching it 96530006, from the old ECU, and copy them into the new one.
So, in other words: add this to evo7base.xml:
Code:
<table name="Immobilizer Hex" category="Misc" address="ffa" type="1D" level="2" scaling="Hex16"/>
Then, open the ROM from your old ECU, and the ROM for your new one. Copy both the Immobilizer and Immobilizer Hex values from the old ROM to the new ROM, then flash your changes. Once you've done that, the immobilizer should function as expected.
The backstory here is that besides the immobilizer value itself that's specific to your keys, there's an additional value (referred to above as "immobilizer hex"; "immobilizer periphery" is probably more accurate) that's specific to each ROM version, and the two are used together with your key to determine if the car is allowed to run.
(We should probably move those instructions to their own page on the wiki, since they're pretty generic instructions for switching from one ROM to another, or for swapping between ECU model years like you're doing.)