First, let me say that the word hack here means "a modification of system resources to make them do something slightly different from the original intent" or something along those lines, and has nothing, really, to do with compromising the security of the system. Unless you screw up. Anyhow, the original hack required you to download some resources, paste them into a copy of the Finder, and then swap the Finders... we're going to be a bit more sophisticated here.
So, as a note, this is all concerning 10.2. The hack was originally developed in some earlier build of X. 10.1(.5 ?) broke the hack, or so I've heard. Now, in 10.2, it works again. The hack no longer works in 10.3 as far as I can tell(I'm still looking, but I have to do it on my sister's comp, which she doesn't like). I am, in addition, pursuing a scripting solution to the hack. In the meantime... well, here it is...
This is easy. Open the Terminal (please don't ask where it is... please tell me you know where it is... if not, poke around in the tutorials for it here, and see if they say). Now, type:
defaults write com.apple.Finder DebugMode 1 and hit return. Basically, what this does is to set the Finder's preferences to be in debug mode. In this mode, there are about 3 changes: 1. The finder doesn't show the standard info windows. It only shows the inspector. 2. The Finder shows a debug menu with all four items disabled. 3. It adds an Icon Size submenu to the View menu. This is what we are interested. It allows the user to, on an item-by-item basis, select the size of icons. The user can select from 16px (Tiny), 32px (Small), whatever the current view options is set to (Normal), 48px(Large... forgive me if I've got the pixel size wrong on this one), and 128px (Thumbnail). Now type killall Finder and hit return to quit the Finder (or, if you happen to have added it, you can use the Finder's quit command). Click on it's icon in the dock to relaunch it. Now you can use the new menu.
I however, find the lack of a normal info window, and the presence of the useless debug menu rather annoying. So...
oh yeah... real quick... to turn off debug mode, quit(or kill) the Finder, then type ONE of these two commands in the Terminal:
defaults write com.apple.Finder DebugMode 0
defaults delete com.apple.Finder DebugMode
First things first... make a backup or two of the Finder... more is good. Ok, now, crack open the Finder by control clicking and selecting "show package contents" (oh, BTW, there's two: the package and the not package... we want the package... make sure you back that one up) and navigate to it's Localized.rsrc file (in your language project, in the resources directory). Copy it to your desktop. Open the copy in your choice of resource editor... preferably one like ResEdit with a full set of built-in templates that open almost everything... ok, well actually, ResEdit doesn't have that many templates, but it has the one we need. In addition, you'll need QuickConvert to open it in ResEdit. Careful, as there are two versions. We want the one that flips the resource and data forks. Drag the file onto it and wait a second. There's no progress indicator, but it works fast... then open in ResEdit. Although it's not necessary, it'd be a good idea to flip it back when we're done.
Ok, now look for the MBAR resources... we want ID 128 (It's called main). Look down to the 4th Menu res id. Right now, it's 131. We want it to be 136. Change it, close, and save. Now, go to the Terminal and kill the Finder (see above)
Here we go... hard core terminal... if you've never done it before anyway... here goes:
cd /System/Library/CoreServices/Finder.app/Contents/Resources/English.lproj
sudo mv Localized.rsrc Localized.old.rsrc (making one more backup... The system will prompt for your Admin password. If you've never entered a password in the terminal before, keep in mind that it does not register visual feedback when typing passwords. No dots... sorry. Just type it all in and hit return)
sudo cp ~/Desktop/Localized.rsrc /System/Library/CoreServices/Finder.app/Contents/Resources/English.lproj/Localized.rsrc (provided you haven't taken too long, the system shouldn't ask for the password again)
Now go to the Dock, and launch the Finder. It should now have the new menu.
Should you ever want to undo this mod, here're the Terminal commands to do it:
killall Finder
cd /System/Library/CoreServices/Finder.app/Contents/Resources/English.lproj
sudo rm Localized.rsrc
sudo mv Localized.old.rsrc Localized.rsrc
Then launch the Finder again in the Dock.