A WordPress blog in CakePhp site.

Create a folder blog in app->webroot in cakephp site.

Upload your wordpress blog in this folder.

Modify your root .htaccess  file in cakeph.

<IfModule mod_rewrite.c>
   RewriteEngine on
   RedirectMatch temp ^/blog/wp-admin$ site_name/blog/
    RewriteRule ^blog$ blog/ [L]
    RewriteRule ^blog/wp-admin$ blog/wp-admin/ [L]
   RewriteRule    ^$ app/webroot/    [L]
   RewriteRule    (.*) app/webroot/$1 [L]
</IfModule>

Now admin URL
site_name/blog/wp-login.php