So what does your rule look-like?
I'd say try something like the following:
Options -Indexes +FollowSymLinks
RewriteEngine On
# Your current redirect that works (I'm guessing)
RewriteRule ^/(.*)/(.*).html /index.php?tpl=$1&id=$2
# Redirect from domain.com/template_style/index.php?id=XX
RewriteRule ^/(.*)/index.php?id=(.*) /index.php?tpl=$1&id=$2
I wouldn't quote me on that, but something like that... Although, from teh looks of it, it's what you already have...