I've been doing this program for the last 10 months and next Saturday is the Tulsa Run, so I wanted to suggest a program for all of you. Please be careful to not overtrain. Do your normal Crossfit WOD's 4-6 times a week and throw in an additional 2-3 Crossfit Endurance WOD a week. So if you go out and try to do a bunch of LSD(long slow distance) training with progressively longer miles on the weekends, you are probably going to overtrain.
CrossFit Endurance suggests:
Running: Start with 8 x 200m repeats working up to 4-5 x 800m repeats... Meaning you should be able to handle this workout and a CrossFit workout in one day. PROGRESSION is the key. For Stamina (tempo and time trial) you should be working on building from about 10 minutes to 90 minutes depending on distance. You will never really need to train much further then the 90 minute mark if working hard enough. Do not be fooled in thinking you only have to train for stamina for 10-90 minutes. If you are a triathlete trying to make the transition into this program you will need to gently progress into it. You are fragile, and this is not conventional strength and conditioining. Once you can handle the workouts by progressing them, you then should be following the www.anaerobicendurance.com site 2-3 times per week single sport and up to 6 workouts per week for triathlon.