Yes. Please post your setup, and we can help you out.
-Year model of car
-ECU used
-Engine used
Looks like the easiest solution for you would be to swap your instrument cluster for one from a 98-99 Accord 4cyl.
The "best" option will run you about $70. It's a box that converts the ECT signal from a steady state to PWM signal. Just google "S2000 ECT".
If you want to go the cheap DIY route, you can wire up your stock ECU to run simultaneously with the F20B ECU, with its sole purpose being to operate the ECT gauge.