I don't think you need to rebuild the driver each time although you do need to tell Linux to load the drivers on boot. It's easy- just add them to /etc/modules. Might look something like so:

Code:
rtc
ac
asus_acpi
battery
button
fan
thermal
usb-ohci
usbmouse
hid
mousedev
serial
forcedeth
i810_audio
agpgart
af_packet
autofs4
lt_modem
lt_serial
Congrats on getting the modem to work.