I guess if there's something wrong with using Goomba and a GBA flash cart, there is a practical alternative after all: the rather poorly-named "USB 64M Smart Card".

http://store.kitsch-bent.com/product/usb-64m-smart-card
http://truechiptilldeath.com/blog/20...4m-smart-card/

(I can't say I was familiar with the rabid popularity of this "lsdj" before I read about this either.)