For those of you who are confounded like I was, Jebediah's patch in #22 seems to work great, at least with ubercart 2.4.

Patching the files threw me for a loop. After much duress here's what I did to get it to work:
1) installed a copy of cygwin that included the patch.exe command line patcher. This one should work: http://sourceforge.net/projects/gnuwin32/files/patch/2.5.9-7/patch-2.5.9...
2) Opened a command prompt on my windows machine (start -> "cmd")
3) Navigated to the folder where my ftp client had downloaded the ubercart attribute files... at the command prompt type in something like cd \website\public_html\sites\all\modules\ubercart\uc_attribute
Once you're in the right folder when you type "dir" you should see the files uc_attribute.admin.inc and uc_attribute.module
4) Edit the patch file provided by jebediah in #22 to fix file paths. In Jebediah's patch file he has the path "/home/jsmith/Downloads/drupal/ubercart_mod/uc_attribute/"... I used a text editor to search and replace for that file path with nothing, so in effect I removed the path to file and left the file names. Since we're changing to the folder where these files are stored we do not have to specify the file path. Line 3 of his patch file changed from
+++ /home/jsmith/Downloads/drupal/ubercart_mod/uc_attribute/uc_attribute.admin.inc 2010-08-17 09:37:28.716809308 -0600
to
+++ uc_attribute.admin.inc 2010-08-17 09:37:28.716809308 -0600
Note there are several places in this patch file that specifies this path so it's best to do a search and replace. I used dreamweaver to do this but any text editor should work.
5) back to command prompt, type the command:
c:\cygwin\bin\patch.exe -p0 < c:\multiplier.patch
^note that the first portion is the location of the patch.exe file (wherever you installed it), the second portion is the location of the patch file (that I saved to c:\ in my case) and the current folder needs to be where uc_attribute.admin.inc and uc_attribute.module are located.
If you executed this correctly you should see a message "patching file uc_attribute.admin.inc
patching file uc_attribute.module". Replace these two files on the server with the patched versions (if you're not doing this on the server itself).

Once installed you can see the Drupal options at /admin/store/attributes/option
Clicking on options and then edit takes you to a path like this /admin/store/attributes/2/options/8/edit where you should see a new option "Multiplier"

Hope this helps someone!!