Check out here http://tuxmobil.org/laptop_manufacturer.html
for a start. There might be one just like yours listed there or similar previous model. Read many of them and you can figure out what you need to do pretty easily.
Kernel should more than likely be ready. Open a console terminal session and plug in the cell phone to computer. Use the dmesg command to see if it is seen and what it maybe defined as. Post output if confused or not.
As far as software the only thing that pops in my mind is rfcomm on USB cell modem.
Check the HCL section here. There might be something in there as well. If not and you get it going please post what you did in there.
Not sure of your phone service provider but Verizon offers low speed 14.4k connection to there service for the price of your minutes. A higher speed service is available for fee. Same with afew others.