HOWTO specify PS1 from the command line when invoking Bash/sh

[Jim Fischer]

Is there any way to specify the value of PS1 on the command line when
launching Bash/sh?

For example: Assume the current command shell is 'X', where 'X' is
neither Bash nor sh. From shell X's command line I want to start a
couple of interactive /bin/sh shells (e.g., a couple of xterm windows
running 'sh' as their command shell) where /bin/sh #1 has a PS1 prompt
of 'ONE>' and /bin/sh #2 has a PS1 prompt of 'TWO>'. Is this possible,
and if so, how is it done?

Jim