My cramps usually come with C/bloating, so I feel your pain!
I think the effect you want to go for here is to get everything moving gently. For me, this means having an IF/SF combo in every meal: vegetable soup and sourdough toast, for example. Also, I drink loads of tea and force myself to exercise for at least 30 minutes a day. I hate doing the latter when I feel crampy and gross, but I feel better afterwards. Walking is fantastic - I think it convinces my colon to flow gently along rather than getting tied up in knots.
As with all IBS-C things, this works the best the longer you do it.
For more immediate relief, it's peppermint tea and a heating pad, with an optional cat on top of the heating pad. I'll also revisit the hypno CDs because they have taught me how to (at least partially) release the cramps and relax.