THX, I found this code to do it
Section ""
Call GetCurrentTime
Pop $0
DetailPrint "$0"
SectionEnd
Function GetCurrentTime
Push $R0
Push $R1
Push $R2
System::Call '*(&i2, &i2, &i2, &i2, &i2, &i2, &i2, &i2) i .R0'
System::Call 'kernel32::GetLocalTime(i) i(R0)'
System::Call '*$R0(&i2, &i2, &i2, &i2, &i2, &i2, &i2, &i2)(.R0,,,,,,,)'
StrCpy $R1 $R0
System::Call '*(&i2, &i2, &i2, &i2, &i2, &i2, &i2, &i2) i .R0'
System::Call 'kernel32::GetLocalTime(i) i(R0)'
System::Call '*$R0(&i2, &i2, &i2, &i2, &i2, &i2, &i2, &i2)(,.R0,,,,,,)'
StrCpy $R2 $R0 "" 1
StrCmp $R2 "" 0 +2
StrCpy $R0 "0$R0"
StrCpy $R1 "$R1-$R0"
System::Call '*(&i2, &i2, &i2, &i2, &i2, &i2, &i2, &i2) i .R0'
System::Call 'kernel32::GetLocalTime(i) i(R0)'
System::Call '*$R0(&i2, &i2, &i2, &i2, &i2, &i2, &i2, &i2)(,,,.R0,,,,)'
StrCpy $R2 $R0 "" 1
StrCmp $R2 "" 0 +2
StrCpy $R0 "0$R0"
StrCpy $R1 "$R1-$R0"
System::Call '*(&i2, &i2, &i2, &i2, &i2, &i2, &i2, &i2) i .R0'
System::Call 'kernel32::GetLocalTime(i) i(R0)'
System::Call '*$R0(&i2, &i2, &i2, &i2, &i2, &i2, &i2, &i2)(,,,,.R0,,,)'
StrCpy $R2 $R0 "" 1
StrCmp $R2 "" 0 +2
StrCpy $R0 "0$R0"
StrCpy $R1 "$R1-$R0"
System::Call '*(&i2, &i2, &i2, &i2, &i2, &i2, &i2, &i2) i .R0'
System::Call 'kernel32::GetLocalTime(i) i(R0)'
System::Call '*$R0(&i2, &i2, &i2, &i2, &i2, &i2, &i2, &i2)(,,,,,.R0,,)'
StrCpy $R2 $R0 "" 1
StrCmp $R2 "" 0 +2
StrCpy $R0 "0$R0"
StrCpy $R1 "$R1-$R0"
System::Call '*(&i2, &i2, &i2, &i2, &i2, &i2, &i2, &i2) i .R0'
System::Call 'kernel32::GetLocalTime(i) i(R0)'
System::Call '*$R0(&i2, &i2, &i2, &i2, &i2, &i2, &i2, &i2)(,,,,,,.R0,)'
StrCpy $R2 $R0 "" 1
StrCmp $R2 "" 0 +2
StrCpy $R0 "0$R0"
StrCpy $R0 "$R1-$R0"
Pop $R2
Pop $R1
Exch $R0
FunctionEnd