Infected machine on dial-up

It transpires a stupid friend of mine did not think he needed any anti-virus
software. I am fairly sure he has been infected.

He only has dial-up so when I go there tomorrow I won't be able to use an
online scanner without spending all day on the Net.

Is there any way I can download something onto my flash pen and run a virus
check from that before I install a virus checker?

Any suggestions appreciated.