Since 4.0.2, Forest configures automatically on render nodes the paths listed in the registry at HKEY_LOCAL_MACHINE\SOFTWARE\Itoo Software\Forest Pack Pro\TexturePaths. As any other paths to assets, these are stored in the 3ds Max configuration Customize - Configure User Paths - External files stored in 3dsmax.ini. The ini file is located by default here:
C:\Documents and Settings\<username>\Local Settings\Application Data\Autodesk\3dsmax\<max version>\enu\3dsmax.ini
It's not necessary to configure these paths manually. When Forest is loaded, it's checking if these paths exist and if not, all of them could be added automatically. If you marked previusly the Do not show this message again check-box to disable that pop-up window, you can revert it to its default value (to pop-up) by setting the checkTexturePaths = 1 in the forestpack.ini configuration file located by default at:
Generally, we recommend to resolve all references used by Forest with the Asset Tracker to absolute UNC paths. It's not necessary, but usually this way you avoid any texture path issues while using distributed rendering.
Also, please see attached maxscript, which will also automatically add these paths (FP & RC) to the .ini file.