Creating a matrix entry with a plugin
In case anyone is interested this is how I solved the problem:

First load the matrix field:

$addressMatrix = craft()-&gt;fields-&gt;getFieldByHandle("addressMatrix");


Then get all of the blocks of the matrix field:

$addressMatrixBlocks = craft()-&gt;matrix-&gt;getBlockTypesByFieldId($addressMatrix-&gt;id);


Next iterate over the blocks looking for a specific handle:

foreach($addressMatrixBlocks as $key =&gt; $data){ 

    if($data-&gt;handle === "address"){ 

    $addressBlock = $data; 
    break; 

    }; 

};


Now you have your block. To get the ID just do this:

echo $addressBlock-&gt;id;