The simple answer, as far as I know, is no. However, keep in mind that I haven’t used MetaStock for around 3 years, when v8 was the current update. It's probably been enhanced significantly since then.
If I may digress momentarily, it was MetaStock that indirectly got me interested in technical analysis, back in 2001. A friend couldn’t get MetaStock to perform a market depth analysis, and I ended up writing a charting package that offers a number of specialist facilities that I can pretty much guarantee you won’t find anywhere else.
Anyway, my point is that MetaStock (at least v8) offers a number of formulae, which can be used to develop custom indicators and "explorations" (scans to find stocks that meet certain indicator-based criteria). MT4, by contrast, is backed by a full-fledged programming language. It’s a bit like comparing Microsoft Excel with Visual Basic; the former, while extremely useful in its own right, offers only a mere subset of what the latter is capable.
Depending on how complex your indicator is, you might be able to rewrite it for use in MetaStock. MetaStock does have its own back-testing facilities, but (as far as I can remember) they work rather differently than MT4 EAs/strategy tester.
