yet another approach

more.rx

9 variable: prefix:CHAR

create prefix:TABLE
  256 allot

: getc:internal  ( -c )  &getc 2 + @ do ;

[ dup @prefix:CHAR == [ drop getc:internal "prefix:TABLE" find drop @d->xt + @ dup 0 <> [ dip cr ] [ drop ] if 0 ] ifTrue ] is remapKeys


: bindTo: ( quote "character" - )
  getc "prefix:TABLE" find drop @d->xt + ! ;

[ cr
  "?        help text\n" puts
  "d<word>  documentation for word\n" puts
  "s        show stack contents\n" puts
  "p<char>  change trigger character to <char>\n" puts ] bindTo: ?

[ "display docs for: " puts
  getToken find [ cr @d->doc 0; puts ] [ drop cr "no docs found!" puts ] if ] bindTo: d

[ "display functions matcing: " puts
  getToken cr (matching) ] bindTo: m