The following patch does this, (i already sent optimize on ccl bit, but since it's somewhat related, i included it too):
swank-backend.lisp (declaration-arglist): Add declaration `declaration'. swank-openmcl.lisp (describe-symbol-for-emacs): Add information about type specifiers. (declaration-arglist ((decl-identifier (eql 'optimize)))): new method.
contrib/slime-parse.el (slime-parse-extended-operator/declare): Fix ability to provide arglist for (proclaim '(...)). Remove unused variables, slightly refactor.