pyrogenic: I was trying to hook up my laptop with my friend's, and that failed, mostly because I don't have enough NICs.
But that made me wonder about making a direct cable connection via the modem, which led me into poking at settings and looking up things on the internet. While I concluded that I probably can't do a direct cable connection over the modem, the poking led me to the insight that I probably could set up myself with a remote dial-up for when my laptop and I are out of range of my router/wireless router.
I do believe that my ISP offers me dial-up gratis when I am away from home, at least up to a certain amount/month, but that will burn cellphone minutes.
And, IIRC, the minutes between home and cellphone are free. I'll have to confirm it with the phone company, but this just might be crazy enough to work.