This is sort of a bunny hood asm. As soon you have an item (e.g., moonpearl) you can use this hack that your speed is also accelerated:

http://bszelda.zeldalegends.net/stuff/Con/bunnyhood.zip

Inside you find 4 different asm:
- moonpearl.asm: speed is accelerated as soon you have the moonpearl in your inventory
- book_mudora_equipped.asm: accelerated speed if you have the book mudora in Y-box equipped
- moonpearl_Rbuttonpressed.asm: accelerated speed if you have the moonpearl in your inventory AND hold the R-Button pressed!
- moonpearl_Lbuttonpressed.asm: accelerated speed if you have the moonpearl in your inventory AND hold the L-Button pressed!
(R-button interferes with the skip monologue asm. If you e.g., bump in an autotalking sprite (upgrade pond or whatever) this monologue is skipped. L-button interferes with the superbomb, but only if you have it equipped, so probably the L-button asm is the better choice).

Note: you need to set the speed values yourself, by adjusting the db table at the end of the asm, e.g.: db $18 -> $30 for fast horizontal and vertical walking