LispOS compiler question

[Emergent Technologies]

In an attempt to bring some life back into this group, I'll post a
question. 

What would be a good compiler to use for writing a LispOS?  I think
the following goals would be nice:

1.  Free

2.  Fairly easy to hack (so the underlying lisp architecture can
change).

3.  Object code portable to Linux and Win32 (for bootstrapping
reasons).

4.  Support proper tail recursion (not strictly necessary for Lisp,
but required for Scheme).


I don't think it would be necessary to have a highly optimizing
compiler.  

I think a simple compiler that output ANSI C in the Baker's
explicit continuation passing style might fit the bill.

What do others think?  Would anyone be able to take some spare time
and write a wimp-ass compiler?

~jrm