I only started studying Japanese recently... But these days, I'm working on the Ruby language, and Japanese turns out to be a big help there. You can find several gaijin learning Japanese to work on Ruby, it turns out.
If you need to pick up Japanese in a massive hurry and you want advice from somebody a few months farther along than you are, keep reading.
First, Get Google Translate
The simplest way to handle Japanese is to let the machine do it. There's a great Chrome extension for Google Translate, and before that you can use it manually (ew.) Some of Translate's output won't make any damn sense. That is normal and expected. But it's still mostly better than nothing.
To get an idea of how useful (and not-useful) it is, I recommend translating this wonderful article on profiling by Yui Naruse. The article isn't available in English, it kinda-sorta works with Google Translate, and you can just about limp through it without knowing any actual Japanese.
So: Google Translate is an okay step one, and really easy. Do that first.
Second, Immerse Yourself
You'll want to be surrounded by Japanese to pick it up. Better, surround yourself with Japanese Ruby stuff.
Google for Ruby stuff and click Japanese links. Read bugs. I'm told there's good Japanese Ruby IRC but I can't seem to find it.
For more, follow Twitter accounts. I've had good luck following Matz, Koichi Sasada and Nalsh. You might also like Yusuke Endoh, Shibata Hiroshi or Akira Matsuda. There are others, and they tend to retweet each other, so feel free to pick up new Japanese developers as you go along.
Twitter offers a second Bing-based translation for each Tweet. Sometimes it's better than Google Translate, sometimes worse, sometimes both will make zero sense. That's how it goes. You can also use Jisho and Rikaikun to translate specific words.
You will, however, start picking up little figures of speech like Koichi's "うーん" (sort of an "uh..." or "ugh..." suggesting that he's tired.) Which is what you're there for - to see Japanese words used by Japanese developers doing Ruby things.
Plus you can start picking apart Hiragana from Katakana and learning common borrowed-from-English words that are used in Japanese. Speaking of which...
Third, Learn the Alphabet(s)
However you start formally learning Japanese, they're likely to start teaching you Hiragana and Katakana, the two easier Japanese alphabets... Or syllabaries. Or whatever you want to call them. Kanji's the really hard one, and you won't learn it immediately. But Google Translate plus Hiragana and Katakana will take you farther than you'd think.
But they'll also teach you to start picking apart sentences into Hiragana, Katakana and Kanji, which lets you start teasing out and learning interesting words, such as "ツール" (tool).
This takes time, repetition and memorization. Which is why you're self-immersing on Twitter and stuff, right?
Also, practice with an app. I like Kana Mind, but there are many.
Fourth, Keep Learning
At some point these stop being "learn Japanese in a massive hurry" tips. Instead, they're just "learn Japanese" tips.
Get a teacher? Yes, it helps a lot.
Study buddies? If you can, definitely. Good study partners can be hard to find. But they're really useful!
In general, yes, keep going.
Thanks to Al Tobey, who helped me with a lot of my initial jump into Japanese. Several of these recommendations were from him first.
And thanks to the ever-friendly Ruby folks, Japanese-speaking and English-speaking alike.
Since you kept reading this far (thanks!), here's a list of Japanese terms from the Ruby bug tracker. I got them from a Ruby developer on Twitter.
まってる -> feedback まだ -> open まつ -> matz なおした -> closed なおってた -> closed なおさない -> rejected