how to load classes from non standart directories?

[eluser]Unknown[/eluser]
Hello,

how can I load the class which is outside of standart directories?

I have a directory structure with many subdirectories.
In each subdirectory can be more files defining various classes.

Example:

Code:

APPDIR/
   mydir/
      subdir1/
         subdir11/
            class1.php
            class2.php
         subdir12/
            class3.php
      subdir2/
         subdir21/
            class4.php
            class5.php
            class6.php
...

I cannot use this:

Code:

$this->load->library()

because my classes are not in standart directories.
I got the error:

Unable to load the requested class

There is any possibility to instruct CI for searching classes in custom directories?

Thanks.