Upgrade MBP to Snow Leopord with external USB HD?

[jhgodwin]

I've been told it's not possible to use a USB drive to boot from and I've read that it can be done on a few different websites. I have the .dmg Snow Leopard file on the external USB HD and want to upgrade my MBP. I pulled the dmg file from the DVD using another computer. My DVD drive is not working on my MBP and I was hoping to find a way to upgrade without it. Every time I try to put a DVD in, it sounds like it is trying to read it but eventually just spits it out over and over. Can I do this and if so, what do I need to do first to prepare for it (partitioning and such)? I've never done anything like this so speak to me like a child!

 

[jpma]

yes, create the partition in your external drive and have SL installed into it.
also possible to boot external and install SL into your macbook pro with that drive.

 

[segers909]

You CAN boot from a USB device on any Intel Mac. On PowerPc Mac's, it involves hacking.
To install Snow Leopard, just go to disk utility, format the usb hard drive in a mac format, then select the tab "restore", drag the icon of the usb stick to target and select the dmg for source. If you get an error about it should be checked first, you can find that somewhere in the menu at the top of you're screen. (can't exacely remember how it's called, but it's pritty straight forward)