You can install LispWorks 6.1 in the same directory as previous versions of LispWorks such as LispWorks 6.0. This is because all the 6.1 files are stored in a subdirectory called
lib/6-1-0-0
.
You must recompile all your code with the LispWorks 6.1 compiler.
Binaries produced by
compile-file
in previous versions of LispWorks such as LispWorks 6.0 do not load into a LispWorks 6.1 image.
LispWorks Release Notes and Installation Guide - 23 Dec 2011