For MT4, why don't you just write an indicator that computes the correlation between two pairs directly? You can plot the correlation and use it on any pair, timeframe, and period of your choosing.

Correlation spreadsheet anyone?

Use this spreadsheet to determine performance of trading strategy over 1 year (250 trading days) with: 1.) Starting account value 2.) Account Risk 3.) Winning probability 4.) Risk/reward ratio I find a strategy with a minimum of 40% winning ...

Systems in theory