installing ubuntu 8.04 from a Live Usb onto iMac

[bigdee973]

this is more of a mac quesiton then it is a ubuntu... but how do i bootup to the usb from a mac? i know how to do this on a PC but cant do it on a Mac. whats the command? i tried booting holding option key but all i get is the macintosh hd and DVD i have installed to boot no usb..usb is recognized though when i log onto mac

[cyberdork33]

this is more of a mac quesiton then it is a ubuntu... but how do i bootup to the usb from a mac? i know how to do this on a PC but cant do it on a Mac. whats the command? i tried booting holding option key but all i get is the macintosh hd and DVD i have installed to boot no usb..usb is recognized though when i log onto mac
It will not boot a "legacy OS" from usb.