Here are the instructions on how to Jailbreak your iPod touch 4G for Mac using RedsnOw on 4.3.2 firmware.
Create a folder on your desktop called Pwnage
Download RedSn0w and place it in the Pwnage folder. Likewise, download the latest 4.3.2 firmware and place it in the same folder.
4.3.2 (4G): iPod4,1_4.3.2_8H7_Restore.ipsw
Extract the RedSn0w zip file by double clicking it.
Connect your iPod touch to the computer and launch iTunes.
Now select your iPod from the list of devices on the left. Now hold down Option and click the Restore button. Restore is preferred as it won’t create any wasted space on your iPod.
Again navigate to the Pwnage folder on your desktop and select the 4.3.2 firmware ipsw. Click the Choose button to continue.
Once iTunes has finished updating your iPod to the desired firmware open the Pwnage folder on your desktop and launch the redsn0w application from the redsn0w folder.
Click the Browse button once RedSn0w opens
Select the 4.3.2 firmware ipsw we placed in the Pwnage folder on our desktop then click Open.
Click the Next button to continue once the firmware has been verified .
RedSn0w will now prepare the jailbreak data
From this window you can select the jailbreak options you would like. But make sure Cydia is selected and click the Next button to continue.
Now plug your iPod touch into the computer and make sure its OFF then click the Next button
RedSn0w will now guide you through the steps to get into DFU mode. You can find more help with DFU mode
Hold down both the Home button and the Power button for 10 seconds.
Release the Power button and continue holding the Home button until RedSn0w detects the device.
Your iPod will now reboot
RedSn0w will then begin uploading the new RAM Disk and Kernel.
Once this is complete you will be notified that RedSn0w is done. Click the Finish button. When your iPod touch finishes rebooting (5 minutes or so) it will be jailbroken with Cydia on the SpringBoard.
[ Image courtesy freeipodtouch4g.co.uk]