I found a VKP patch for Z550i (R6CA009) that gives it the Play/Pause (& radio) button by simulating it on the volume up/down button(s). Here it is:

CODE
; Z550  SW-R6 CA009
; button "Play / Pause" on the long ticking upwards or downwards
; Default - down, to change cut out the first row, second uncomment
; (c) IronMaster

452577C8: 41 3A; retention down;

;452577C4: 3E 3A;deduction of up
;Just as it is, hold the button down volume button is the Play / Pause
;If they want with the volume up button, put a; in the first line, and delete; of the second line


But the problem is that this works only when the flip is open. As you know Z550i is a clamshell phone, and you need this Play/Pause button mostly when the flip is closed!
Can anyone please look into the patch & correct it to work also when the flip is closed. All work by IronMaster is highly appreciated! (Its damn difficult to get VKPs for Z550i)

EDIT:Sorry, the button works when a song is playing and you close the flip with the Media Player running, my bad. Whereas when the flip is open, the button works at all times.