I found the following over at ousob.com. It appears as part of a larger article which seems to have the documentation for the whole PKSFX suite. It looks like you run the executable and then specify any flags followed by the path to extract to and, optionally, specific named files from within the archive to be extracted if you don't want them all.
PKSFX Command Summary
Command line syntax and options are the same as PKUNZIP. The options
listed below are offered by a self-extracting file.
Syntax: pksfx [option] [d:\path] [file]* [file]*
PKSFX indicates the name of the self-extracting file you are executing.
No options are necessary if you wish to simply extract all files to the
current directory. If you wish to extract the contents to another
directory, indicate the drive and/or path the files should extract to. To
extract only particular files, indicate the name(s) at the end of the
command line.
Options:
@listfile.lst Specify list of files for extraction*
-c[m] Extract to console*
-d Re-create directories stored in .ZIP file*
-l Display software license agreement*
-n Extract only newer files*
-o Overwrite existing files
-p[a|b][c][#] Extract to printer*
-s<password> Decrypt with password*
-t Test file integrity*
* Indicates options not available in the PKSFX Junior and PKUNZIP Junior
programs.
Options should be placed after the self-extracting files name. If
multiple options are used they must be separated by a space and each must
have its own option indicator (either - or /).
All options behave in the same manner as they do with PKUNZIP, with one
exception. The -s option cannot accept keyboard entry. A password
entered with a self-extracting file must be able to be entered from the
command line.