You can import file/s from your computer by selecting one or more files (no need to copy/paste). All suggestions and requests will be considered. Please try the support site. It supports both v3 & v4 GreaseMonkey functions. There are some minor consideration regarding the include patterns which is explained in the included Help file.
I tested "Google Hit Hider by Domain" and it installs but wont enable it due to include error. FireMonkey uses the dedicated Firefox API and the API doesn't allow wild card TLD (ie http*://www.google.*/*). That has to change in order to be able to run the script.