Also, if you don't like IC2 experimental, you might consider Speiger's IC2 Classic, which has versions for Minecraft 1.6.4 and 1.7.10: [Port][1.6.4|1.7.10] IC2 Classic by Speiger
I am 100% sure that MC1.2.5 already had geothermal compat for BC Pipes! I know that because the test world where I first tested the very first lightning rod also had a geothermal setup with BC Pipes, which did crash due to API issues.