I've had a chat with them and it seems you can use the 'Custom' indicator from the menu to reference the indicators in MT4. But one of the problem is that ZigZag has 3 variables and the 'Custom' indicator only provides 1 variable for you to key in - see below.
I've emailed the support team to see if they can come out with a solution. Otherwise the guy said he can help me to get the coding team to code for me - sounds exciting.
As to your question - it goes back to my trading method, which is based on Richard Wyckoff. As you might be aware, his methodology is based on price action trading and if you get a chance to read a book called "Trades About to Happen" by David Weis, he has come out with buying and selling wave exhaustion, that was just one of his methods to identify potential turn for the market.
Anyway, he has created a Weis Wave indicator (see below) which demonstrates buying and selling wave based on cumulative volume, and the wave direction changes based on the number of pips you pre-define. So as you can see in the following example the effort vs reward scenario where high volume down bar (first down blue arrow) has no follow through, i.e. high cumulative volume did not generate further selling pressure compared to the previous up-wave.
And his Weis Wave indicator is very similar to the ZigZag indicator, which led me to try this indicator just now. Because in the EA lab what I did was to count back to a certain number of 'n' bars to define the lowest and highest point. One big disadvantage of defining this way is that it can only work on M30 timeframe, because obviously when you move onto higher timeframe, i.e. H1 or H4, the higher resistances/supports could be clustered into the counting period, if that makes sense.
So using the ZigZag could solve the issue and I just did a quick test on the chart this morning and it fits perfectly to my text which I note down yesterday. I did not deliberately put it down on top of each turning point after testing ZigZag.