ubuntu x64 refuses to install a 32-bit app.

ubuntu x64 - well, a flavor of it: ultimate x64 1.8 - refuses to install a 32-bit app.

To be precise: I need to use Open Object REXX. I do know there exist many good scripting apps that properly function in linux.

But ... to explain mi position:

• I'm a writer. To be precise: I'm writing maths texts. The medium I use is pure xhtml, with all sorts of bells and whistles.
  I do not use Flash. I do not even use Java. All the game (emerging windows, tabbed interfaces, suggestive hints, many complicated interactions with the reader) is done by means of orthodox xhtml .
  Of course, I do use javascript - ECMAscript. Also, I make a moderate use of mathml to display some math formulas.
• To minimize the boring repetitive task of writing complicated code multiple times, of course I use a scriptable editor.
  After many trials, I have chosen PsPad editor for the work I do in Windows systems. It's a comfortable tool that depends on Windows Scripting Host (WSH). PsPad have several quirks and flaws, but these are quirks and flaws of Windows ...
  One of the advantages I found in PsPad (mainly due to its rely on WSH) is the ability of combining several flavors of scripting: jScript, VBScript, and REXX among others (in fact: any scripting language registered by the WSH engine).
• I have used REXX for many years. In fact, I became a REXX user as an OS/2 user. I love the simplicity of plain-English REXX sintax, and - to all my effects - REXX is the language for scripts.
  And, yes, I know there are several scripting engines out there, all available in ubuntu linux (I have a MS degree in Computer Science, by the way).
  But the fact is, I am involved in writing Mathematics, and not in studying a new language.
• I don't understand why ubuntu x64 refuses to install and run REXX 32-bit. By the way, both win Vista x64 and win xp x64 run 32-bit apps. It's a flaw in the design of linux?
• I have found several scriptable editors that run on ubuntu linux. Two of them support calling scripts, on the basis that their engines are supported by the system. Now, do you see what's my trouble?

I have posted this inquiry in several ubuntu-specialized forums, with no practical answer. Can you help me?