I had this question also in the Metal Slug Anthology thread but I think that that whole conversation is dead because no one responded.

does anyone know if they sell a PS2 to gamecube adapter that lets you swap the analog to a digital pad. I have the neo geo arcade stick for ps2 and I want to use it with my Wii and Metal Slug Anthology game, however the adapter I have recognized the controller as digital, (The game only accepts the analog controller for movement) buttons work but no movement. I really hope there is an adapter that lets you switch between the two. As far as I know the PS2 Neo Geo Arcade Stick I has Does NOT do the swap. However the instructions are in japenese so I can't say that it doesn't though I am 90% sure it does not.