Here's what I have coded:

oVar.ZipFname = allt(m.att_file)

oVar.WinZipCmndLn = ALLT(oVar.WinZipLoc) + ;
" -e -o " + ;
ALLT(oVar.ZipFname) + " " + ALLT(oVar.ZipTargetPath)

oProcess = CREATEOBJECT("API_APPRUN", allt(oVar.WinZipCmndLn),"","NOR")
oProcess.LaunchAppAndWait()
WAIT CLEAR
oVar.ZipStatus = oProcess.CheckProcessExitCode()
oProcess = .NULL.

RELEASE CLASSLIB PROCESS