Newer software versions include a parts counter but you can use your idea to do the same thing.
Put in the MISC event as you have described and also put in a MISC event like this:
PRINT[COUNT IS #1]
Look in the upper left corner of the display under the RunTime clock to see it.
Be aware that you have to zero Parameter 1 (or whichever of the first 99 parameter numbers you use) yourself and that Verifying the program will add to the count.
Put the MISC events at the end of the program so that halting the program in the middle won't also add to the count.