The formula for correction to cold temperatures is to add 4% altitude (QFE / AGL) for every 10 C below ISA from the reporting source.
You will find it in Jepps ATC chapter, and in most JAA operators manuals.
My experience is only scandinavian + canadian operators understand and perform this correction as a part of SOP.
The number of blank stares I have received from co-pilots, training captains and examiners elsewhere in the world when briefing this procedure, is just mind boggling.
A quick example common in many airports these days:
A sea level airport reporting a temp of -10C will need a correction of 10% (ISA -25, 4+4+2%) to MSA, MEA, MORA and all altitudes below.
If your MEA is 5000`, this is now corrected to 5500.
Flying a glideslope in these conditions will easily show you how important the corrections are.
If published GS intercept is 3000`at 10 NM, maintain 3300` indicated until 10NM and you will see the GS intercepting excactly at 3300` and 10NM.
Outer marker passage on the GS will occur at 2200` instead of 2000`.
A 200`DA will only need to be corrected by 20`, which is hardly noticable.
Flying non-precision approaches in very cold temps can easily make you a CFIT statistic. Remember the MSA is 1000` regardless
of terrain below/above 5000`.
Descending to the MSA of 8000` in ISA - 10C will only give you 200` AGL clearance. Add some wind, and I hope your GPWS is capable of saving your hide!
You as a pilot better do it, ATC will not. The only exception is being radar vectored in Canada, where they correct MVA for non standard temps.
Flying baro VNAV in these conditions will require you to have the FMS correct by manually enter aiport temp if possible, or applying the corrected altitude to the approach altitudes in the FMS.
A life saving rule of thumb is to add 10% to MEA, MSA, IAF, DA , MDA etc. when the airport reports temps down to -10C. Add 20% when down to -30C. Any colder, get the book out, or stay home!