I suppose this scenario would work:
You must be granted a MySQL user account with the privilege "SELECT" (or "ALL") from the SMF database where the block is you want to copy. Your Web server's hostname or IP address must also be permitted to access the MySQL database where that SMF database is housed. You can use this PHP script-
mysql_connect("your-servers-hostname/IP", "your-given-username", "your-given-password") or die(mysql_error());
mysql_select_db("their-SMF-database") or die(mysql_error());
$sql = 'SELECT * FROM 'smf_tp_blocks' WHERE ( ('smf_tp_blocks' . 'id' = ?? ) ) ';
and where "??" (no surrounding quotes in query) would be the numerical value of the block you wish to copy from their table/database.
In PHPMyAdmin or whatever you like, create a new row in the "smf_tp_blocks" table of your database and enter the same numerical value in the "id" field (both must match). Another PHP script (which I can not write
) can then import the row's field values you got from the above script which dynamically gathered the block from the other SMF forum you wanted.