I know there is no such syllable as "त" in English, but still is there any way we can write it with English alphabet, using any accent or anything? Like it's done for Spanish or Italian I guess?
Also How to put a macron over vowels (ā) in Windows 7?
I tried the Alt code from this answer- Is it possible to enter macron (ā) and caron (ǎ) diacritics with USA international keyboard?
But that's clearly for Win XP. And that's an old answer. How do I do it in Win 7? Maybe there is some way now.

a''. (In Word). – Hastur May 21 '16 at 08:08iintoIor-->in one arrow... You can add your own,for examplea''forत. If you need a system wide solution you can create a global command for that letter e.g. CTRL-ALT-SHIFT-A or whatever... – Hastur May 21 '16 at 08:50Left Alt + Shiftto switch the input language when multiple input languages are enabled in Windows 7. Cannot you find a suitable keyboard layout? (Maybe you have to try all the combinations included AltGr + Shift... ) – Hastur May 21 '16 at 08:59