Quote: "Realy, that works?"
There are many scenarios... too many to list. Changing/adding to a name by any degree is not as important as whether or not you make financial gain from someone else's trademark/notoriety. A lot will have to do with the use of the current mark and what sector of business it implies.
The good news is that codex is a common word...
codex (Latin caudex for "trunk of a tree" or block of wood, book; plural codices)
which gives you much more room to work with, especially if you intend to add more to it, such as for example; Lead-Codex or Codex Data Systems.
On to the Logo. I would suggest that you flesh out the full name and a by-line (ie:"Solid Business Leads") to go with it before you play around with design, as these things will lead you in different directions. When you have a full understanding of what you want to say with your logo, you'll be better equiped to make that statement/design.
Brian.
!retupmoc eht ni deppart m'I !pleH