Is there a tag for total track number? (iTunes: track 3 "of 10")

Support
8

CTRL+K is your friend then.

But if you've lots of albums to do then you can use this autohotkey routine I wrote:

It accepts the dialog without having to press it using the new shortcut CTRL+N. Just make sure you've set the dialog up first they way you like and run it once for them to stick.

Then use AHK script:

;
; Short-cut: CTRL+N
; TRACK turbo Auto-Renumberererer
;
#IfWinActive ahk_exe Mp3tag.exe
    ^n::
    Sleep, 500
    send, {LAlt}
    send, {o}
    send, {Down 1}
    send, {enter}
; This next line auto accepts the AR dialog
    send, {enter}
    Return
#IfWinActive

Instructions on usage: Keyboard shortcuts