You can get an application to auto launch once installed by modifying your .pkg file as follows. Find the .exe within your project you want to run, in this case it's "HelloWorldBasic.exe" and add the ",FR,RI" options to the end of the line:
....S60_3rd_FP1epoc32releasegcceurelHelloWorldBasic.exe" - "!:sysbinHelloWorldBasic.exe", FR, RI
FR Means "File Run"
RI Means "Run on Install"
You can even launch a file on un-installation as well, I found this link on the Symbian website which provides some useful information.