My initial post a bit dated now, since starting MTX some 4 or 5 months ago, haven't got a problem with scalp. My hair has actually gone from dry to greasy ! Amazing that ... haven't noticed significant hairloss as a result of MTX and so far, so good am pleased with results.
The elemis and Kérastase products certainly seem to have helped in the past;
I've used diprosalic as advised by Derm cocois at night, wash out flakes and then apply diprosalic solution which was pretty effective.
I've also got some Rainforest (SLS free) shampoo from the Body Shop which lathers well - not sure it would work alone tho if scalp is pretty scaly.
Mine (my scalp) has never been noticeable, only to the hairdresser - its now cleared with MTX but I continue to use more expensive products hoping that somehow they make a difference. Ooo forgot, have used T-gel as well as advised by others here - worked well - xamiol tho caused my P to worsen. Just goes to confirm what we suspect - what works for one might cause a flare in another.
Hugs
BB