if you are using mac OSX you need to have US extended selected in the international control panel of the system preferences. for first tone it's alt a, second is alt e, third is alt v, and forth is alt ~.

Do you want to use it to label falling tone . Example \ ai _ an

http://py.kdd.cc/ This website can translate 'chinese' to 'chinese pinyin'。

you mean like this? ā á ă à you can type using word, then take from the symbols list you can memorize the ascii code for each then use alt+code (will work even with notepad)