Your first task will be to determine which version of IOpener your relative has.
I can only speak with respect to the V5 IOpener. With the V5 IOpener, you cannot get into the default BIOS or the Sandisk. You MUST use a new V5 BIOS (cant get into the BIOS as with previous versions) and to use the system, you must boot from an alternate hard drive... ie. you MUST modify the heat sink configuration. It takes a hacksaw and 15 minutes to cut away a strip about 2" long by 3/8" wide from one corner. Once exposed, you can put a laptop drive/win98 in it /on it and set it to autoboot and login to ISP.
I have another post "how do you boot the sandisk on a V5?", as I cant figure it out myself. Its clear that some folks are running jailbait on their sandisk, and booting it. Its not clear that they are doing it with a V5 Iopener. If so, there might be some options there for you to explore. In that case, you are STILL going to have to expose the IDE header, but you might not have to cut the heatsink. You could, temporarily, put a normal hs on the cpu and hook up an ide drive long enough to install the sandisk, and then put back the original hs (heatsink). the cpu gets hot fast, so a heatsink needs to be on it while powered up (but the original hs covers the ide header).