Hey - alternatively you can do this natively with the at command:
at now +3 days <enter>
/path/to/script <enter>
Ctrl-D
The at command actually waits for a Ctrl-D (EOF) for termination. You can feed it an entire command by echoing want you want to run and piping that to the at command - or you can just type - I find it to be easier personally.
Edit:
But note - everything on every line is executed all at once. So for instance, if you want a script to run and then have another script run after, it won't work.
For instance, I was trying to run a dbexport once on an AIX/Informix system - once the dbexport was done, I wanted to tar and then gzip the file. I tried the following:
at 0500 Tomorrow
cd /backup/dir
dbexport my_database
cd my_database.exp
tar -cvf ../my_database *
gzip -S .gtz /path/to/storage my_database
Since all the commands dumped at once, the export ran fine, but the rest of the commands failed because none of what it was looking for was in the right place yet.
I ended up just taking the code above and putting into a script and then running that with the at command, which worked fine - but don't expect at input to be run sequentially.