In your post install script you can create a symbolic link from your log file to /var/logs

For example, let's say my helloworld application writes a log file to root called fancy_output.log.

To view this log create this link ln -s /var/log/fancy_output.log /fancy_output.log

Your resulting link will look like this: fancy_output.log -> /var/log/fancy_output.log

Once helloworld creates the file fancy_output.log which will now appear in /var/log/fancy_output.log, you can now view the file via the commands 'show logs', and read its contents via command 'show log name fancy_output.log'