Before calling any of the Objective-C interface functions, the runtime system must be initialized. This is done by calling ensure-objc-initialized, optionally passing a list of foreign modules to be loaded. For example, the following will initialize and load Cocoa:
(objc:ensure-objc-initialized
:modules
'("/System/Library/Frameworks/Foundation.framework/Versions/C/Foundation"
"/System/Library/Frameworks/Cocoa.framework/Versions/A/Cocoa"))
LispWorks Objective-C and Cocoa Interface User Guide and Reference Manual - 15 Dec 2011