How to format external HD and install software on it? Help, please?

Question

When install programs on my Mac there is only one option for installation - on the internal HD, the other drive plugged in the computer appear with exclamation mark - ie they are not available for installing anything on them.
I want to be able to install some small programs , or a web browsers on external drive , just to see how they works, etc.
How to format an external HD or USB flash drive (if its size is enough)
so it is possible for install a program on it instead on the internal hard drive?
Thanks to all!
Ema

Answer 1

That's the theory. Note that you'll wipe the external drive in the process, so if there's anything you want on it, get it copied elsewhere first. It’s always wise to back up any important stuff on your MacBook of course before doing anything like this (but not to the drive you’re about to use!)
With the drive connected, open Disk Utility, highlight the external drive in the sidebar (that's the drive itself, usually listed by the manufacturer's name and the size of the drive). Select 'partition' in the tab bar, ensure the drop-down on the right is set to 'Mac OS Extended (journaled)', give the partition a name in the box above that (like 'ext HD' or whatever). Click on the 'options' button below the diagram and select 'GUID Partition Table' (very important - it won't boot SL with any other setting). then click the 'apply' button.
Once that's done, close DU and insert the 10.6 install DVD in the MacBook (or whatever the Mac is). After the licence agreement there’ll be a picture of Macintosh HD, but underneath should be a button saying ‘show all disks’. click that and select the external drive, then click install and follow the instructions.
Note that if you do this with the grey install disk that came with the computer, you will only be able to boot that computer with it, as it’s model specific. If the install DVD is a black retail one, it should theoreticaly boot any Mac (but note the licence conditions).
Once the install is complete, boot from the external HD by either selecting it under ‘startup disk’ in Sys Prefs, or by holding down the alt key during restart and selecting the drive from that screen. You can then install any progs you want and try them out from there. (don’t forget to reset the startup disk when you want to reboot from the MacBook).
If you don’t have a DVD, or you want a duplicate of your existing system, go with the clone idea, using CCC (not because it’s better than SuperDuper, but because it’s free if you don’t mind putting up with a few ads while it’s working!)
Hope that does the trick for you.