Storing all Sylpheed data in another location

I've been experimenting with Sylpheed, and am impressed with its functionality.

Because it can store sensitive information (such as your email password in plain text) in its ..\Data\Profile folder, I want to have it store all its data in a location that is not a subfolder of ..\PortableApps\SylpheedPortable.

I have been trying to figure out how to do this.

According to ..\PortableApps\SylpheedPortable\Other\Source\Readme.txt, you can create a file named SylpheedPortable.ini "next to" SylpheedPortable.exe. Does "next to" mean "in the same folder"?

If so, this initially looks like it would work, but the trouble is that it only allows defining "AdditionalParameters". I think, however, a command line parameter needs to be changed, not an additional one added.

What looks required is, within ..\PortableApps\SylpheedPortable\App\AppInfo\Launcher\SylpheedPortable.ini, replacing:

CommandLineArguments='--configdir "%PAL:DataDir\%\profile"'

with:

CommandLineArguments='--configdir "X:\OtherLocation"'

Is there a way to accomplish this using "AdditionalParameters" or a different technique?

If not, will such a change to ..\PortableApps\SylpheedPortable\App\AppInfo\Launcher\SylpheedPortable.ini need to be made every time Sylpheed is updated by the PortableApps launcher?

Is there an easier way to accomplish the goal of having Sylpheed store all of its data in another location?