What do you mean by “combine”? You just turn the plugins ON and they should work fine. Gator Cache is for page caching while the plugin you mentioned compresses css and js files.
Most of those plugins probably work like WP HTTPS, by buffering all content, then running something to modify the content before page load. This is basically what a caching plugin would do as well, so there may be conflicts. Will take a look, if it’s a fairly well-used plugin will implement a compatiblity fix.
Unlike the other popular minify plugins, this one uses output buffering to modify the content. This presents a compatibility issue with GatorCache. However, with the latest version, 2.0.9, GatorCache will recognize the WPMinifyFix buffer handler and adjust the content accordingly so the two plugins will be compatible.
