I don't put them into lager when they have 4-6 points to drop. I lager them when they are finished and rested (diacetyl, acetaldehyde etc)
Fermentation wise they will possibly still keep fermenting at 1 degree but fermenting is not lagering. They will ferment some sugars ale yeast won't but don't need to be at 1 degree in order to do so. Ciders will ferment right out if allowed to do so so the difference between lager and ale yeasts is less relevant.
The yeast (both ale and lager) will, as far as I'm aware, still help condition the beer at lower temps but my point is simply a counterpoint to your post which said 'You can lager cider?? never thought of that before, might be worth a look'.
All I'm saying is - of course you can lager it. You can lager anything. Lagering is not the same as fermenting cool/cold (although I do ferment my ciders cool/cold and THEN lager).