You get the “plain ol” k4 interpreter automatically when you download the 32-bit KDB+.
From the “q)” prompt just enter a single backslash “\”
That drops you into the k4 interpreter.
To return to the Q interpreter, enter a single backslash again.
You can also get the “plain ol” k2.8 interpreter as follows:
Join the Kona Developers Group on Google.
View the entry titled “Availablity of 32-bit version of k (for comparisons to kona)”