One day of running is 3-5 miles. Can be done on the same day as a crossfit workout. Pace doesn't matter, but it shouldn't be a slow slow slow shuffle.
Second day of running should be done on it's own day (probably - depends on how you're feeling) and playing soccer can sub for this day of running:
3 x (100m + 200m + 400m)
Work : Rest ratio of 1:2. Rest exactly twice as long as it takes to perform a given
distance in a set.
For example, run 200m in 35 seconds, rest 70
seconds, run 400m in 1:15, rest 2:30, etc.
So: run 100 in 15 seconds, rest 30, run 200 in 35 seconds, rest 70, run 400 in 1:15 rest 2:30 = 1 SET
You need to do 3 SETS. There is no extra rest after you finish the 400 ... just rest 2:30 and then go straight back to running 100 m. The rest period is standing rest, so just hang out until your time is up and then take off in a sprint.
Be sure to adequately warm up before beginning. Warm-up period should take NO LESS than 8 minutes.