The Express Engine kernel can be built with any ANSI Common Lisp compliant development environment.
The GUI version, unfortunately, requires a specific commercial Lisp environment. The CAPI based GUI requires LispWorks.
Eventually, the GUI will be reimplemented in CLIM (Common Lisp
Interface Manager), thereby allowing the system to be built using any
Common Lisp environment which includes CLIM. You can try out the CLIM
version type typing 'expressow
Express Engine is now compiled! To run it type (expo:expresso)