That said, if ALL you want to do is connect a keyboard and mouse, there MIGHT be a possibility. But it's ugly.
First, you need a PCMCIA card to add USB to your PowerBook.
Second, you need a D-Link 'mac-compatible' USB Bluetooth adapter.
Third, you need access to an OS X-running Mac with USB.
To make it work, you need to first plug the D-Link adapter into an OS X Mac. Then you need to run the Apple Bluetooth Firmware Update. Then you need to pair your keyboard and mouse. THEN you need to get USB working on your PowerBook. FINALLY, you need to plug the Bluetooth adapter into the USB port on the PowerBook's PCMCIA card. Then, with any luck, it will let you use your Bluetooth keyboard and mouse.
BUT, even if you get it to work, it will ONLY work for keyboard and mouse. That's because the Apple Bluetooth Firmware Update tricks the D-Link adapter into pretending it is a USB keyboard and mouse until proper Bluetooth drivers are loaded. This is so that a USB-only computer (such as an early iMac,) can use a Bluetooth keyboard and mouse early in the boot process.
Information gleaned from http://www.os9forever.com/Bluetooth.html (Where the guy is/was trying to write OS 9 Bluetooth drivers, but the latest update is over a year old. But even he is only trying to support USB Bluetooth adapters, not PCMCIA ones.)
(Oh, and be careful shopping for PCMCIA USB cards. Most of them are the newer 'CardBus' type that won't work in a 1400.)