I setup a spammable round-robin key (do-not-advance-for-X-seconds). When something needs interrupting I spam that key ("R" in my case) while also hitting the DPS spam. For instance: I'll hit the interrupt first, so it turns from 4444444 to R4R4R4R4 until interrupt fires). This is very similar to daanji's method but I avoid the stop-casting.

Most fights that have interrupts that are vital to catch are either time based or have a nice long warning, so I'll just spam my DPS key while also spamming my interrupt key - since windshear is off the GCD there is very little DPS lost. While providing slightly more control over timing as opposed to just weaving in an interupt every 1.5 seconds or every 2 seconds etc.