reposync and making internal repos. (and then using kickstart) is better option, IMO.
But if you want to just download, then something as simple as:
yumdownloader $(cat myfile)
...might well do it. yumdownloader is in the yum-utils package. If you need to use yum/yum-downloadonly then you can do:
yum --installroot=/tmp/my-installroot --downloadonly install $(cat myfile)
...that will get you all the deps. too (not sure if that's what you want). If it doesn't fit on the command use yum shell:
perl -pe 's/^/install /' myfile > myfile-shell
echo run >> myfile-shell
yum --installroot=/tmp/my-installroot --downloadonly shell myfile
...but again, I think you really want to have usable repos. on your yum machines.