Trekker should be installed in its own directory, so as to avoid any possible conflicts. You can create this directory before installing Trekker portable, or the installer can create this directory for you. To have the installer create the directory for you, use the Browse button in the installer to select the existing directory to be above the Trekker directory. For example you selected "c:\programs" using the Browse feature, then type in after the "c:\programs" a directory divider like "\yourname" where "yourname" is the name of the directory you want created for Trekker. By placing Trekker in its own directory it will also make the process of removing Trekker portable easier as then it is simply a matter of deleting the directory (and all its content) that you created for Trekker.
It is recommended that if you are using Trekker for splitting and merging pdf files that you ensure enough disk space on the drive to which it is installed. The amount of space needed depends entirely upon the amount of split pages you are processing via the join list. Also please install Trekker on reasonably fast media for best results.