Not sure if this is exactly what you are after but it may help. It is an applescript I picked up somewhere.
tell application "Terminal"
activate
-- Get a window that's not busy.
-- If there are no open windows, open one.
if (count of windows) is greater than 0 then
repeat with currentWindow in windows
if currentWindow is not busy then
set targetWindow to currentWindow
end if
end repeat
else
do script ""
set targetWindow to window 1
end if
-- Do command 1.
set firstCommand to "ls"
do script firstCommand in targetWindow
-- Open a new tab.
tell application "System Events" to tell process "Terminal" to keystroke "t" using command down
-- Do command 2.
set secondCommand to "pwd"
do script secondCommand in targetWindow
-- And so on...
end tell
