OCX Files and Inno

[jcis]

By reading the DEP file (RICHTX32.DEP, it's in Windows System folder)..

; Default Dependencies ----------------------------------------------

[RichTx32.ocx]
Dest=$(WinSysPath)
Register=$(DLLSelfRegister)
Version=6.0.88.4
Uses1=RichEd32.dll
Uses2=ComCat.dll
Uses3=
CABFileName=RichTx32.cab
CABDefaultURL=http://activex.microsoft.com/controls/vb6
CABINFFile=RichTx32.inf

[ComCat.dll]
Dest=$(WinSysPathSysFile)
Register=$(DLLSelfRegister)
Uses1=

[RichEd32.dll]
Dest=$(WinSysPathSysFile)
...

ComCat.dll is a VB Runtime file, it's present in all installers, but the one you need here is RichEd32.dll, so in INNO SETUP I think it should be:

; RichTextBox Control
Source: YourRedistFolder\RichEd32.dll; DestDir: {sys}; Flags:  sharedfile
Source: YourRedistFolder\Richtx32.ocx; DestDir: {sys}; Flags:  sharedfile regserver restartreplace