Help need to lower my fan turn on temp

[rhdv8]

Hi I have a LS1 from a 2004 GTO in a Mazda RX7 and when I spec'd the ecu fan temps I thought I would be able to use the low and high speed fan. But as it turns out, as I don’t have a BCM to trigger the low speed I am only able to access the high speed setting, which is a bit high for the only fan. Is there anyone out there who is near to North London/Herts/Essex and has the necessary software who could make the change for me in return for your expenses and some beer tokens?
Many thanks.