The coal man has been 
We'll build a Pyramid - as I'm not sure what the Yasso entails but you'll get the drift.
Log into Garmin Connect
Hover over the 'Plan' tab on the top line and a drop down will appear.
Select 'Workouts'
Click 'New Workout'
Give it a name (Not too big - like 'Pyramid' or 'Yasso')
Make sure that the Workout Type is showing 'Running'
Click 'Add Step'
To start with we will have a Warm up section. This will allow you to warm up as part of your session and will record your distance at the same time.
Under 'Step Type' select 'Warm Up'
Leave the duration at 'Lap Button Press' and the target as 'No Target'
Click 'Add Step'
Step Type 'Interval', Duration 'Distance' and set the distance to 0.40 km (or if you're set up in miles 0.25)
Target 'Pace' - you can now set the pace window that you want to stay in. For example, if you want to run at between 5:00 and 5:15 per km then you would enter 5:00 in the first window and 5:15 in the second
Click 'Done'
Click 'Add Step'
Step Type 'Recovery', Duration 'Lap Button Press', Target 'No Target' - Click 'Done'
Click 'Add Step'
This time add an Interval for 0.6Km at the same pace range.
Click 'Add Step'
Add another 'Recovery'
Carry on adding Intervals and Recoveries for 0.8Km, 1.0Km, 0.8Km and 0.6Km
Last step.
Add an Interval for 0.4km but this time, but dont add a recovery - I'll explain why later.
Once this last step has been added click 'Save'
You have now added a Pyramid workout which does 400, 600, 800, 1k, 800, 600, 400 with a warm up.
Make sure that your watch is linked in to your PC and click 'Send to Device'.
Presuming the 305 works in the same way as the 610. Garmin Connect will search for your watch, find it and then you can click send Workout.
To Use the workout:
Find it on your watch and select 'Do Workout'
Then start your Warm up run. Once ready - click the Lap button and run like hell.
When you reach 400m your watch will beep at you and you will go into recovery until you next press Lap - when you need to run like hell again.
Progress through your workout - if you run too fast or too slow, your watch will shout at you.
When you have done your last 400m, you watch will let you know you have finished your workout. The reason that we don't have a Recovery or Cool down here is just in case you lose track of where you're up to.
You can now just Cool Down in your own time.
Hopefully, the 305 will let you do all of the above - fingers crossed.
Edited: 13/02/2013 at 12:25