Not that it really answers the question at hand (I have never used a hardware RAID card and probably never will), but I have to ask: Why?
Mdraid is far more flexible and is supported out of the box. For mdraid, seeing individual drives is exactly what you want.
What benefit does a hardware/firmware raid card confer that you actually need? Neither of the cards you mention have a BBWC or any other features that Linux software RAID lacks, and will only serve to tie your array to a specific piece of hardware. The performance advantages of a cheap hardware raid card vs. softraid on a modern CPU are questionable at best, and I have seen more than one that are actually slower.
If you're going for a raid card because you're coming from Windoze (and Windoze softraid sucks hard
), forget all that. Linux mdraid is excellent.
If you really do need 3rd party drivers for the install, and you have them compiled for the kernel the installer is using, you should be able to load the .ko from a USB drive by dropping to a shell prior to running the installer. Remember to ensure it is also copied to the installed system and included in the initrd when installation is done. If you want to boot from such an array it will also need to be supported (and loaded) by GRUB.
If all you have is the driver source you will first need to compile it on the livecd or another Debian machine with the same kernel.
Really, mdraid is far easier to set up - and you can run your array on any machine that has enough ports.
As for building a custom install cd, yes, there are many tutorials
on the www, and there's more than one way to do it. For a single use though, it's probably easier to just load the driver from a USB disk.