It isn't going to be easy. You need to open both programs and copy and
paste from Pagemaker (PM) to Publisher. You will lose all formatting when
you do so. Creating a PDF file won't help as Publisher or PM won't open
them natively.
I do not believe that you would be able to save the PM (although I stopped
upgrading PM in version 6.5 and it won't SaveAs anything other than a PM
file or a template) file in any format that would be readily useable by
Publisher. Publisher (up to 2003) won't open any file near to what PM will
create.
While Adobe Acrobat will create a Word Document from a PDF file (printed
from the PM program), again the format would probably be lost and you also
would need to have the full Acrobat program on your computer.
Sorry for the bad word but hope the document isn't too big you need to
convert.