Not that I know of (i've never bothered with it) I think you'll find that the RPMS file/directory is just the individual packages (plus a few others) that are in the main distro.
What I would suggest though, is that during the install, tell it not to download the updates. Then when the install is complete, make sure that your net connection is working, then go here
and follow the instructions. So then when you've got the closest mirror's for main, contrib, updates and plf (oh and if during the process, you get any error's whereby it won't let you use the mirror that you've chosen, just follow the process again, but only for whichever source gives you error's), you then just go into mandrake control centre (configure my computer)>software manager>updates and then let it settle down. When it's got the facility/dialogue box opened, make sure you check the boxes for security bugfixes and normal updates.
You can then go about installing the updates. Just to be thorough, I install all of the updates (I understand that it only offers you updates for stuff that you've got installed on your system). In fact, I fired up mandrake control centre to make sure that I'm up to date, and explaining it correctly. It looks like I'd better get the latest kernel and sources installed.
So hopefully it'll go OK for you.