I did it with my A1200, with a hypercom, u can get much higher than normal dial up if ur shring the broadband connection.
If u use miami(which i did) , its not to diffcult, im sure there is a readme file with miami that tell u how to do it
it was years ago , and i cant rember how to do it sorry and it was wiht win2kpro, but should eb the same for xp