If you do a search on google for something along the lines of "use cell phone wireless modem" you'll find several links giving information about doing this. Please realize that you really should check the information out for yourself with your specific cell provider. Rate plans and included options change all the time and sometimes, if you have a plan that's "older" (you've been on it awhile), your plan specifics could be different from what's currently being offered. Having said that, I think you'll find that you can do what you're hoping to.
I am facing some financial obstacles and looking at all possible cost-cutting measures. One of them is to cancel my landline telephone at home and use my Verizon cell phone exclusively for phone calls. The only reason I need a landline is for dial-up Internet access. Verizon has a product called Mobile Office that allows you to connect your cell phone (mine is a Samsung a650) to your PC and access the Internet. I don't have data access on my cell phone so I would be stuck with the Quick 2 Net option making essentially a voice call to my ISP and it is, I understand, very slow. But for the sake of checking my e-mail, that would be adequate.
I am not in a position to upgrade my cell phone for Web access, subscribe to cable Internet, buy a Blackberry, Bluetooth or any other handheld Internet device of any color. (See first sentence about financial obstacles.) But before I cut the umbilical cord on my landline telephone I would like to know if the Verizon Mobile Office really works with a dial-up modem. I am willing to invest the $40 in Verizon Mobile Office in order to save $35 a month on my landline phone if indeed it works.