Start out tempoing 400 metres per day.
At the end of each week, if it feels any easier, start running it 2 seconds faster. Make sure it still feels like tempo pace.
Once you stall, take note of your pace. Call it X.
Increase distance by 10% every couple weeks until you're at some mileage Y.
Once you're steadily running Y miles/day at X pace, run the last 400 2 seconds faster. Repeat until your last 400m tempo stalls (i.e. feels faster than tempo).
Now increase that finishing tempo by 10% every couple weeks until you're running the full Y miles/day at the new pace.
The basic idea is to increase training load consistently. Start at very low volume. Every couple weeks increase speed or volume, but only speed or volume. Can anyone tell me why this wouldn't work for distances over 1500m?