Unfortunately, it will not work without a modded BIOS. The default BIOS on Toshiba portables from that era will only accept IDE hard drives that identify themselves as a Conner "CP" model drive, and even then only two or three specific capacities. You can't just slap in any old non-Conner branded IDE drive and have it work, even if it is otherwise a supported capacity. I have no experience with actually using them, but as mentioned there supposedly are modified versions of the BIOS that remove the IDE whitelist and allow you to use any IDE drive, which would include CF cards with an adapter. Installing the modded BIOS would require physically replacing the BIOS ROM chips on the motherboard with EEPROM chips flashed with the modded BIOS, as the T5200 BIOS cannot be reflashed like on modern systems.