I'm not sure what level of CfE you're meaning (although technically it shouldn't matter), but this is what we're doing at the moment on our BEd at the RSAMD so I thought I'd throw in my tuppence worth! This is more with classroom teaching in mind rather than instrumental tuition, though.
We've just finished our placement in primary schools, where CfE is basically 5-14 but possibly a bit less detailed - I don't actually know the guidelines yet so I could be talking nonsense here! I think in the primary school the big link with music to the rest of the curriculum is through topic work - singing songs about the topics they're studying and maybe making sound pictures and that sort of thing. Listening doesn't really seem to be done much in primary but it would work into the historical aspect, what music people from the past listened to, how they might have danced to it

In instrumental tuition this could probably work its way into theory more than performance, if you did something with note numbers you could incorporate it into thinking about intervals and triads and things I suppose. If you wanted a link to topic work it would be easiest to start with a history slant, if the child is learning about a certain period in time you could talk about what context the piano/instrument was used in at that time and play some pieces from that era, discuss the style etc. I suppose you could have some more tenuous links to language by making words from the note names - I was watching the film Magnolia recently and one of the rounds in the quiz show is that notes are played to the contestants and they have to say what word they spell, relating to a picnic - I forget the third but the other two were egg and bee.
When it comes to secondary I'm much less familiar with the guidelines and abilities, and I think although CfE is aiming for cross-curricular study the way that lessons are taught in secondary schools will really inhibit this - which to my mind isn't really a bad thing, at the secondary stage I think pupils should be making most of the cross curricular links for themselves if they are interested, unless it pertains specifically to the unit being studied (for example sound in physics).
I can't even think of that much to do at the secondary level... thinking of G5 Theory, maybe setting a poem studied in English to a rhythm/melody? Doing the musical terms in other languages, world music as part of geography... The four capacities are a bit easier - Successful Learners, Confident Individuals, Responsible Citizens, Effective Contributors (woo I remembered them all!) - success in AB exams is very successful in the grand scheme of things, and the performing element builds confidence. The other two are less obvious but I've never cared much for them anyway haha.
I'm afraid that most of what I've suggested might be a bit obvious for what you were looking for... I suppose music by its nature is very cross curricular so it shouldn't be very hard to integrate into CfE, although I think in reality it is unrealistic in the secondary classroom - music teachers can easily make their subject very cross curricular, but will the other subject teachers be able to reciprocate? And more importantly, will they have the time, resources or knowledge required to do it? A lot is asked of teachers nowadays - although I suppose that's an opportunity to set the pupils the tasks to find out more if they really want to.
Sorry, this has been a horrendously long post - ironic since I'm meant to be writing about music history and only re-enabled the internet so I could look up African Sanctus. Oh well, there's still 9 hours before it's due in, and yes, it IS 3.25am. Oh dear.