I'm not sure where you want to send keystrokes to..
To the current running app or
any other application by WindowTitle or hWnd?
Theres an example on CodeProject, like
Sending-Keystrokes-to-another-Application-in-C
There're also, as you mentioned a lot of KeyRecorders AutoClickers, like Clicador
aso lots more...
SB-Extensions that use SendKey are eg.
LDTextWindow.SendKey (which you know)
Perhaps also look at
FCKeyboard... (in Fremy ext.)
like FCKeyboard.SendKeys ( ups, just found it's deaktevated)
SPKeys together with
SPExtra.SendKeys (in SayPlus ext from LDExtensionMgr, rather old, recompiled and untested)
SayPlus_v1.2.zip
KeyboardBuffer... (in Piccolino ext. also rather old and recopmiles for SB1.2)
RZGraphicsWindow (in RezohRu ext, perhaps you find something usefull)
I'll upload the Piccolino and RezohRu extensions for SB12 for you in a while, sorry that .xml files are prob. in german only, trying to find the engl. versions.