z-man,
what sucks about the startalk was the fact that you can only do the greetings in house. there is no way to change it remotley.
as for having an alt greeting, you can record up to 6 diffrent greetings.
log into startalk, go to aa, greeting, greeting again, choose which greeting you want (1 in main, 2 is lunch, 3 is night, 4 is holiday 5 and 6 are anything) you can change any of them, after going through the steps of recording the prompts go back to the start point then go to aa, and change the day, lunch, etc... prompts to the greeting you picked.