Lexus immo off possibilities

[Lexas]

hello. need some help on possible immo off solutions. my friends having hot rod car project. they installed engine from Lexus LS400 year 2000. most wires from the loom removed, left only what need for engine, immo, gearbox and clocks. car was starting without problem. but now immo start giving some problems. sometimes it starts and works, but sometimes starts and cuts out straight away and immo light is blinking. So maybe is any solution to make it immo off or any emu exists? some info:
engine from 2000 Lexus Ls400. engine code 1 uzfe
ecu 89661-50440

Thanks in advance