In reply to Ethan Thomas:
The IML is a trekking qualification for leading walking parties on non glacier terrain in the middle mountain.
It does not cover, via ferrata, technical mountaineering, rock climbing, ice climbing or alpine climbing.
I did the training in the 1990's in Benasque, Spain with PYB. At that time you needed to already have your summer and winter ML. It was later changed to just winter ML training and has again been changed several times with lots of extra modules... The course was fun in that it took us to all the areas we shouldn't really be going to, though few folk got the wrong idea and thought these are the areas we should be going to!
The winter bit is a bit strange in that it covers snowshoeing and avalanche awareness but not the use of an ice axe and crampons. It's inappropriate for winter hillwalking away from the pisted ski areas or marked trails. It doesn't cover crossing glaciers or using ropes and harnesses.
On the plus side the IML is now recognised in most of Europe and in many parts of the world.
As for how long will it take, my case was different as I never bothered going for assessment until several years later.
Starting from scratch if you go through the UK system and gain the required log book experience it'll take several years at least. I know several people working in the industry full-time who have flown through the schemes. It's taken them at least three or more years and an awful lot of money.
For full details see
http://www.mountain-training.org/award-schemes/international-mountain-leade...
From the MTA website:
"International Mountain Leader Award Overview
This award trains and assesses candidates in the skills required to lead parties in mountainous areas,including snow-covered Nordic type terrain of the “middle” mountains but excluding via ferrata, glaciers and terrain requiring alpine techniques. The IML builds on the Mountain Leader Award, which candidates must hold. To operate professionally outside the UK, IML-holders must be a member of an association such as BAIML..."