Usage:
/REQUIRE spell.tf
/SPELL_LINE
Keybinding: ^[s
After executing "/require spell.tf", typing "^[s" will call /spell_line to report any misspellings in the current input line. /Spell_line can of course be bound to other keys with "/def -b".
/Spell_line assumes your system has a program called "spell" that reports misspellings in its standard input.