How do I set my mac to ask what disc I want to boot from without having to hold alt?
rEFIt


  rEFIt is a boot menu and maintenance toolkit for EFI-based machines like the Intel Macs. You can use it to boot multiple operating systems easily, including triple-boot setups with Boot Camp. It also provides an easy way to enter and explore the EFI pre-boot environment. 



rEFIt allows you to sync partition tables
customize:


set default  to boot from
define wait time before a boot option is selected 
configure the rEFIt boot screen