Murray - For me a Buy Blocker in anytime frame prevents me from buying. But for a short term trader, I would probably recommend shortening the Monthly Buy Blocker period.
Normally if a Monthly buy blocker is activated it means that there is the potential for a large drop downward. I have the Monthly Buy Blocker set for 2 months unless of course the price gets back to the UTL. Like right now the SPX still has not made a Monthly EMA 3/8 bull crossing so for the Monthly things are in limbo right now. My current Monthly Buy Blocker expires at the end of this month, so something should be sorted out by then. Now Buy Blockers hae no effect on the short side.
Of course going short in SPX Cycles is another long discussion.
The Buy Blocker component is the newest addition to the SPX Cycle system. It was established based on lessons learned. If you look at the current SSO long positions I am holding, If I would have had the Buy Blocker component at the time, it would have prevented me from some of those buys.
As for your question on the MACD EMA input. The MACD I use is the (12,26,9) which is a standard MACD, those are each EMA's, the 12 EMA - 26 EMA is the Macd line which is the Blue Line on the chart and the other line is called the signal line.