save the below script in say /usr/bin directory as netscape. chmod it to 755 and point the netscape button on the panel to this script. Note that my netscape browser is installed in /usr/local/netscape. Works fine for me and I can as many browsers as I want without going through profile manager box.
if /usr/local/netscape/netscape -remote "ping()" 2>/dev/null
# Uncomment one of the following lines according to the desired behavior:
# - replace the current page
# - open in new window
# - open in new tab
exec /usr/local/netscape/netscape -remote "openURL($1$location)"
exec /usr/local/netscape/netscape "$@"