Equivalent to top -ua
You're right, top has changed since 10.6 (Here is the man page for the top on Snow Leopard)

Now, to access to the accumulative mode you have to 


start top
type c to change the current mode 
type a to set the accumulative mode (and enter to validate the input) 


To sort by CPU time, use the -o option :  top -o time

About the second part of your question, I a bit curious. Accumulative mode counts the CPU time since the start of the mode. So I will do it for 10sec if you wait 10 seconds etc.