Ahhh....
I've done this. Trust me, your heat, battery.... Wait, so you said to disregard that? xD
You could say it's all been a placebo effect, but I think's it not. A guy ran benchmarks, and it proved the overclocking method worked. I don't get disconnected in multiplayer in Modern Combat 2: Black Pegasus anymore on the loading screen.
I ASSUME NO RESPONSIBILITY NO MATTER WHAT!
Instructions:
1) SSH into your device.
2) Go to /private/etc
3) Find "fstab". (no quotes) Backup that file.
4) Right Click>Edit
5) Start a new line ABOVE the part that says /dev/blah blah (you get the point)
Now, copy and paste this on that new line:
su
alpine
sysctl -w hw.cpufrequency_max=620000000
sysctl -w hw.cpufrequency=620000000
sysctl -w hw.cpufrequency_min=420000000
Change alpine to your root password.
The first 3 digits of the long numbers are the Mhz.
The first line is the frequency in Mhz you want the iPhone to run on.
The second line should be same as the first.
The third line is the speed you want the iphone to be when sleeping, etc.
So now, the fstab should look like this:
su
alpine
sysctl -w hw.cpufrequency_max=620000000
sysctl -w hw.cpufrequency=620000000
sysctl -w hw.cpufrequency_min=420000000
/dev/disk0s1 / hfs rw 0 1
/dev/disk0s2 /private/var hfs rw 0 2
NOTE: DO NOT CHANGE THE LAST 2 LINES! DO NOT COPY MY LAST 2 LINES! (dev/blah) THEY MAY VARY- CHANGING THEM WILL NOT LET YOU BOOT YOUR DEVICE!
6) Save.
7) Reboot.

I will upload my fstab if requested.
Karma me if I helped!