散々お騒がせした796です。解決したのでご報告申し上げます。
892=896さんのご指摘通り、UNIXClassPath.txtを修正すればうまくいきました。

参考リンクは
http://developer.apple.com/techpubs/webobjects/WebObjects_5/ReleaseNotes/ReleaseNotes.html
のReference 2619370 の部分です。

Reference 2619370
Problem　： WebObjects applications launch with the incorrect Java VM on Solaris and HP-UX.

Description　： On Windows, Solaris, and HP-UX, the Java VM that is used is determined like
this:1. The CLSSPATH.TXT file inside the application wrapper appropriate for your platform
contains a line starting with "JVM". If the path specified by this line is absolute, the
JVM specified by the path is executed.2. If the path specified by the "JVM" line is relative
(for example, if it's simply "java") the operating system resolves the full path of the executable
according to the PATH environment variable.In some installations, the PATH environment
variable contains paths to two or more different Java VMs. As a result, your application may
launch with the incorrect VM. This is not a problem on Windows; the WebObjects installer on Windows
sets the PATH environment variable correctly.

Workaround ： Be sure that the path to the correct Java VM (JDK 1.2 or later) appears before
paths to all other Java VMs. Alternatively, you can edit your application's CLSSPATH.TXT file to
specify the full path to the correct JVM. Warning: Recompiling the project will overwrite this rule.