Here is a site where you can read up on proven tactics for catching marlin in Cabo as well as reviews and contact information for some of the best charter services in Cabo San Lucas. Make sure to download the last 2 issues of the interactive magazine, save it to your desktop and open it with Acrobat Reader, that will activate the links in the magazine. All the ads and web addresses are "hot" so that one click takes you to the advertiser or information links within the articles. For a load of videos on fishing in Cabo, make sure to check out the video links on the home page, top center.
I personally reccommend a few charter services in Cabo and they are:
http://www.minervas.com
http://www.gueritasportfishing.com
http://www.cabosbest.com/Bad-Company
Depending on what your budget is, one of them can certainly take care of your needs. Just let them know that Richard Chudy of CabosBest referred you, they'll take extra special care of you.
All the best!
Richard