First thing to try is: Just turn on bluetooth on your phone. The system will ask if you want the pluto software on it. That should do an auto install. This works with the Series 60 phones--there's no software to install manually, it's all automatic.
If it doesn't, ssh to the Core and run:
hcitool scan
You will see:
Scanning ...
00:60:57:48:4E:E2 Nokia
Then run the PhoneInstall script with the mac address followed by the .sis file (the symbian app):
/usr/pluto/bin/PhoneInstall.sh 00:60:57:48:4E:E2 /usr/pluto/bin/Pluto_S60.sis
You will see:
1 06/19/05 10:21:42 /usr/pluto/bin/PhoneInstall.sh (server) SIS '/usr/pluto/bin/Pluto_S60.sis' uploaded to '00:60:57:48:4E:E2'
If that fails, use scp to get the .sis file and send it over the phone manually using whatever utilities came with the phone... the application is on your core in /usr/pluto/bin file: Pluto_S60.sis