Help with my regex

From: Jason Kinkade (jkinkade_at_datashelter.net)
Date: 09/30/04 

Date: 29 Sep 2004 17:09:33 -0700

I want to match any non-whitespace character between the letters of a
word.

"te.?st" will obviously match any single character between "te" and
"st" including a space and nothing. I want that, but excluding the
space.

I tried everything, like /te(.?[^\s])st/ doesn't do it, cause I still
want "nothing".

Thanks.