Sure you can do it. You just have to train consistently and have a plan. Getting to run 6 miles shouldn't be a big deal, like someone else said, you can train for a Marathon in 6 months, but you have to run them after swimming 1500m and biking 25 miles.

Took me 5 months to get ready for an olympic, and I couldn't swim at first, plus a long ride for me meant 5-6 miles on my hybrid. I could run though, so at least I had 1 out of 3. Sounds like you have 2/3.