To type directly with the computer keyboard:

• Type G for ng & J for ñ
• Type ç or z or sh for ś
• Type A, O, U (or aa, oo, uu) for ā, ō, ū
• Type Y and R for -ya and -ra
• Type -k, -m, -l, -n, -p, -r, -t for the final consonants
• Type M for ᰵ (anusvara) & MM for ᰶ (anusvara)
• Type H for ᰶ (ran)
• Type _ for ᰷ (nukta): it's placed after the consonant and before the consonant with a diacritic mark (-ya, -ra)
• Type / or | for ᰻ (danda) and twice for a double danda

Download & install the font Noto Sans Lepcha