Create crontab and use crontab for schedule

I figured out how to create a crontab entry from within python, by simply running the bash command (echo '...' | crontab e) with the os.system module, and also how to remove again (crontab -r).
The only problem is that crontab -r purges the whole crontab-user-file, and I have not found a way to only remove the desired crontab-entry.

Any suggestions?

I'm looking for a hint in the gnome-schedule source, but until then, it would be cool if some of ya' could point me in the right direction.

UPDATE
I didn't get much out of gnome-schedule, but I found a way of using crontab -l to do the thing.
First you pipe crontab -l in a file, then you do the changes on the file, and then you pipe the changed file back via crontab -.
It works really great!

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Okay, so I figured out than what I need, was to specify the display environment for the crontab.

Code:

*/2 * * * * DISPLAY=:0.0 /home/cb/Documents/Projects/gnotify/gn.py

I also discovered that it only needed to have chmod +x, and not everything else like adding crontab to its permissions group and that stuff.

UPDATE
But I'm still looking for some enlightenment on how to add/remove crontabs from the python app.

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Chris Buchholz