Windows – Bypass keyboard,mouse input and let SendInput pass

I'm making user definable key macros to a program. (Those macros are limited to that program.)

I'm using TApplicationEvents to record key messages. And then use SendInput to play them back. But I need to disable mouse and keyboard so it wouldn't interrupt playback.

I can't use JournalPlaybackProc and JournalRecordProc because they are subject to UAC, UIPI in Vista and Win7.

Is there a easy way to block mouse and keyboard input while still using SendInput. (A way that doesn't need heightened privileges.)

Also I need one escape key that stops playback.

EDIT:
TControl.Perform didn't work because it ignores hotkeys.

I thought of using reserved nibble (bits 25-28) in WM_KEY messages, but in the windows documentation it says it's reserved and do not use. What could be the consequences.