BoltWire has an amazingly powerful little tool called the replacetable that actually only takes one line of code in engine.php.
It allows you to define strings you want to replace in the final output of the page. To use it, define a find and a replace value. The following lines are actually used to insert the robotBlock code in the page header.
$BOLTreplaceHTML['replace'] = "<meta name='robots' content='noindex'>\n</head>";
Note that you are not limited to inserting content in your page header. You can use the replace table to modify any string in your site. This feature is case sensitive.