Limera1n not appearing? Cydia not installing?
This is the thing you're doing wrong. When you are running the limera1n installer on your PC, notice how you need to hold the "Home" button? DO NOT LET IT GO UNTIL THE IPOD COMPLETELY RESTARTS. Keep the damn button held down until you finish the entire jailbreak. Now, just unlock your device after it reboots, limera1n should be sitting there. Fire it up, download Cydia (should reboot or respring). Open limera1n again, install Cydia. Your iPod should respring now. Afterwards, install Cydia for a second time. Allow it to respring. Now just reboot your iPod (Hold the power button for 3-5 seconds, slide to power off, start it back up again). If Cydia fails to appear after this step, reboot again. Cydia should be sitting there and you now have a jailbroken iPod Touch 4G.