You need a "memory" class so you can Read/Write to the memory of the target process. Most importantly. Do you know about memory and how to access the memory of another process? The Windows APIs required?
Once you have that, the code will look something like
Dim addrPtr As UInt32 = ReadUInt32(0x0012F5C4) '' Read 4 bytes from target process --> 4 bytes are an address : ptr
Dim finalAddr as UInt32 = addrPtr + 74 '' is that supposed to be &H74 ? The offset
Sub HackOn()
WriteInt32(finalAddr, 297633)
End Sub
Sub HackOff()
WriteInt32(finalAddr, 197633)
End Sub
?