Use the command line, set it with whatever options you want. Just use task scheduler to schedule it, browse to find the appropriate command names. I'll leave it to you to find out exactly what the commands are. XP doesn't have scandisk though, it has "chkdsk", which can't actually make repairs to your system partition while the OS is running, only during bootup. It also doesn't deal well with open files I've found. So scheduling it may be less than helpful.
A program such as Norton Utilities may allow real scheduling of disk checks and defrags, but they only do as good a job as the ones in XP, because they use the same APIs (making NU pretty much just a different GUI for Microsoft's programs). DiskKeeper and other commercial defraggers also allow scheduled defrags.