I've just released an update to my ruby library called 'littlewire' which provides access to most of littlewire's features in ruby. One of the more interesting additions is that now it includes a commandline utility called 'littlewire.rb' which has an install command. Enter 'littlewire.rb firmwares' to see which firmwares are available, then run 'littlewire.rb install latest' for instance to install the most recent version of littlewire on to your digispark. It does the upload using a ruby implementation of the micronucleus bootloader upload app, so it doesn't need to compile any binaries or have access to your Digispark Arduino IDE. You don't need to fuss around with hex files or any of that, and when installed properly it's available globally on your computer. It requires ruby 1.9 or 2.0 to work.
If you happen to have a digispark with a nunchuck shield and a nunchuck, I highly recommend installing 'latest-beta' (or '1.3' if that's out when you're reading this) then running `littlewire.rb racer`. Let me know what you think! I had fun making it ^_^