I've done this for Windows XP, not Windows 2003, but it should be a similar process.
To slipstream a 64-bit program on a 32-bit os you can use nlite, but it needs the .net framework to support it and both the 64-bit iso and the 32-bit version of the iso, because you're going to swap the 64-bit version of a certain file with the 32-bit version. (If you don't have the iso image, you can copy the cd to a folder on your hard drive and use that with nlite.) In your case, you need a copy of the 32-bit version of the Windows 2003 iso (or copy of that cd's files). If you don't have the 32-bit version you can download a trial version of 32-bit Windows 2003 r2 sp2 here:
http://www.microsoft.com/downloads/details.aspx?FamilyId=1B9FE9E4-1D57-4698-A5CF-DB271ED6D90A&displaylang=en
Or if you're a college student or high school student, you can get a free copy from Microsoft's DreamSpark program.
http://www.microsoft.com/presspass/press/2008/feb08/02-18GSDPR.mspx
The step by step instructions (and screenshots!) to do the slipstreaming are on this web page (including the links for nlite and .net framework):
http://www.msfn.org/articles.php?action=show&showarticle=49
Instead of slipstreaming the Windows service pack, you're slipstreaming your raid drivers.
Here's the problem with the 64-bit program: nlite can't integrate update.exe because it's compiled for 64-bits and nlite is operating on a 32-bit system. (Note: update.exe is the file for Windows XP, so the name might differ for Windows 2003.) The solution is to swap the 64-bit update.exe in your source folder with the 32-bit update.exe (from your download listed above) and let nlite integrate the 32-bit files when it slipstreams. nlite will leave the 64-bit files alone and just copy them to the destination folder once it integrates the 32-bit files.
When that's done, use your cd burning software to copy the iso to a cd. Install Windows and you won't need to worry about the situation with the F6 function and floppy drive for the raid drivers, because the cd already has the drivers on it.