Sorry for not answering earlier (I was on a trip). Look into the file 'mysql.lsp' in the newlisp source distribution. It gives you function definitions and examples on how to interact read/write with a MySQL database.
look at the bottom of the file, where a function 'test' is defined. Updates and inserts are done using SQL in the 'query' function. 'query' is probably a misnomer, perhaps it should be renamed to 'sql'.