Yes you can create your own plug-ins to 'interpret' files for FileLocator Pro, using the same plu-in functionality that FileLocator Pro uses to read certain file types.
A sample plug-in called SamplePlugIn.TailDataInterpreter can be found in this sample C++ Visual Studio project:
http://download.mythicsoft.com/flp/sdk/SamplePlugIn.zip
The plug-in reads the 'tail' of any file associated with the plug-in, which in this case has been associated with the .log file type.
The ReadMe.txt file contains more information about the project.
NRCreateInstance
You may note that there's an exported function called NRCreateInstance. This can be used by FileLocator Pro to create the object without going through COM registration. To identify that a plug-in supports NRCreateInstance specify the name of the DLL in the nonreglibrary element of the XML, e.g.
<nonreglibrary>SamplePlugIn.dll</nonreglibrary>
Custom Extensions
Since version 8 there is another option for enhancing FileLocator Pro's file reading functionality. Custom Extensions allow you to specify a command line to process a given file format. For more information please see:
https://help.mythicsoft.com/filelocatorpro/en/index.html?custom-extensions.htm