In order to play any Gameboy or Gameboy Color games you can just use the eLink software to put them onto the cart. I have an eLink cart (1gb) and have owned a couple of them (i give them away to family and friends as gifts). As long as you have the software to the eLink you can put them on to it, as well as NES roms, and Text Files.
If you want to put the Hacks onto your eLink, make copies of the original roms, then patch one of the copies. When you open the eLink software (assuming that you've gotten the updates), click on the tab that says "EBOOK&SIMULATOR". When you click that tab you'll see the followinf options below:
~ Ebook (with buttons underneathe that say "open text folder" and "add to burn list"
~ PocketNes (with buttons underneathe that say "Open NESROM folder" and "add to burn list"
~ GBC/GB EMU (with buttons underneathe that say "Open GB/GBC folder" and "add to burn list"
You'll want to click on the button that says "Open GB/GBC folder". That'll open a window that you can drag and drop your hacked gameboy or gameboy color game into.
Then you close the window, and click on the "add to burn list" button next to the "open GB/GBC folder" button. A screen will pop up with the "official" name of the rom, you can change that to whatever you'd like.
After that it's ready to go onto your eLink rom cart, and you can play it!
FYI the eLink Cart has no video or mp3 abilities, it was in the original idea for it, but was never fully developed for it.