I have never changed at my seat but am now thinking it might be possible in CS .
The upstairs forward toilets on the A380 are a dream for changing .
Any others demand a bit of contortion .
I do an odd dance routine when taking off my trousers / pants and trying not to step on the toilet floor by using my disposable slippers . Any tips would be welcome !
On my last two flights the crew have kindly pulled the curtain across the galley / exit crew rest area which makes for a good changing zone .