Time - look at your watch when you start, and when you finish.
Distance - try some online mapping software such as mapmyrun.com or alternatively the fitness maps here on Spark www.sparkpeople.com/resource/fitness_maps_
to trace your route. Once you know the distance of your more common running routes, you can probably work things out even more quickly.
Personally, I prefer the calculator at www.caloriesperhour.com/index_burn.php
just enter any two of speed, distance or time, and it will work out the rest. You can then manually enter the calories burned into Spark.