For those who want to try. I have the buttons directly on the External_GPS Skin file. Kalt has the menu pop up separate skin file for destination and stuff.
These are the buttons assignment in my External_GPS.skin file.
Code:
B05,0,78,78,50,"SENDKEY;{ENTER}||GETFOCUS","Menu"
B06,0,128,78,50,"SENDKEY;{ENTER}{ENTER}{ENTER}||GETFOCUS","Address"
B07,0,178,78,50,"SENDKEY;{ENTER}{ENTER}{DOWN}{DOWN}{DOWN}{ENTER}||GETFOCUS","POI"
B08,0,227,78,50,"SENDKEY;{ENTER}{ENTER}{DOWN}{DOWN}{DOWN}{DOWN}{DOWN}{ENTER}||GETFOCUS","Favorite"
B09,0,277,78,50,"SENDKEY;{ENTER}{ENTER}{DOWN}{DOWN}{DOWN}{DOWN}{DOWN}{DOWN}{ENTER}||GETFOCUS","History"
B10,0,326,78,50,"SENDKEY;{ENTER}{ENTER}{LEFT}{ENTER}||GETFOCUS","Cancel Route"
B11,0,376,78,50,"SENDKEY;{3}||GETFOCUS","Toggle 3D View"
B12,0,426,39,50,"SENDKEY;{UP}||GETFOCUS","Zoom Out"
B13,39,426,39,50,"SENDKEY;{DOWN}||GETFOCUS","Zoom In"
Oh yeah, with SENDKEY you gota be carefull which windows get the focus.

[edit]BTW, this is for Routis, but it should work with Iguidance.[/edit]