"In advanced economies, this debate centres on whether the central bank should care about asset prices in addition to consumer prices. In most EMEs, the exchange rate is the most important asset price. Our basic message is simple: EME central banks should care about disequilibrium exchange rates; they should deploy all available instruments to achieve the twin targets of price and exchange rate stability"

why EME's might need to stablize forex movement :

"First, emerging markets may have more fragile balance sheets – essentially they are less well hedged against currency risk – so depreciations may engender financial distress and even bankruptcies and adverse effects on economic activity."

"Second, they may be less flexible, so that when the exchange rate strengthens and the traded goods sector loses competitiveness, this may have permanent effects on the economy even if the exchange rate later reverts to its initial level."

but have they the supply of foreign currency large enough to hold off a big sell
 of their home  currency ?

only if a they are small and b the imf will lend them unlimited foreign currency 

likely ?

do i need to ask that ?