K100 is tricky as you can have immo on or off and not easy to change the settings. He is most probably supplying you with an ecu from another vehicle with K100 fitted and switching immo off, which leaves you with the flashing key.
Ideally you'd need immo turned on for the new ecu and then get Honda to code it, but it leaves you stranded. With a kpro you can turn it on yourself with a laptop so makes it easier to code afterwards.
Easiest way would be to send your ecu off to have the K100 installed and then get it mapped after that. But if you're booked in already I'd see what Jesse would suggest, I'm not sure how it could be switched back on easily.
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