|A modem is a device that is provided by your ISP and connects to your highspeed ADSL/Cable. It modulates and demodulates the signal.|
Taking one of these with you in your travels will do you no good.
I suspect you really mean a wireless network interface (aka NIC) which is a different kind of device that allows you to connect to an existing wireless network. If your friends NIC can be installed on your laptop, and made to work, then yes, you can use it. But this would have to be a USB or PCMCIA device and you would have to have at least one USB/PCMCIA slot on your laptop that is not presently being used. You would also need the drivers for said NIC in order to make it work. You would install those after physically connecting the NIC.
I highly recommend you try it out before you leave on vacation. It's better to leave with it working, then it is to get somewhere where you'd like to use it and discover you can't get it working by yourself.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.