These examples explain no more than my original post, but here are some that do not do what I want:
on HOTLINK will match all of the following: "e", "he", "ello" and "hello".
on $^*:HOTLINK:/(e)/:*:{}
$regml(1) will return "e" when it finds the word "hello", but $1 and $hotlink(match) will return "hello". The entire word "hello" will be 'hover-able' (the mouse turns into a pointing hand).