Firstly, you need to be sufficently happy you can actually use mIRC sockets, if so..
When the bot gets a link, immediately it opens a socket (sockopen) and goes to the website..
and on sockread, you can recieve a variety of results, but the two basic ones you want to look at is,
HTTP/1.1 404 Not Found, and, HTTP/1.1 200 OK
if you recieve an OK then, you can add the host/site, to a text file and then at the end of the day, or even immiately you can open another socket to YOUR site, which would run say, add.php?site=www.thissite.com and your PHP would take over and add it to mysql..
Alternatively, you can look at *?* google.com, for a mIRC script that connects to mysql from mirc and do it that way..
..if this hasnt helped at all, do feel free to post again and ill give you an example of the code.