Here's what I did, which was based on the "Arguments" thing.
Create a shortcut to the Blockland Launcher. Locate this shortcut on your flash drive.
Open up the "properties" dialog box for this shortcut.
See that box that says "target"? You need to add an argument to that.
Best explained by an example: If my flash drive uses Drive Letter E, and BlocklandLauncher.exe is stored under "E:/Blockland/New_Folder" , then I would add the following to the end of the target box:
-profilePath "E:\Blockland\New_Folder"
So replace that with the path that your Blockland Launcher and related files are stored in.
It's a pain to load it up if you swap drive letters, though; you have to create a new shortcut for the new drive letter and it has to recheck all your addons; booting up Blockland can take A LOOOOOONG TIME when switching drive letters and even if it's the same letter it can still take a nice ten minutes.
Hope this helps.