Frostfire macros?

[Multibocks]

You will need two buttons. For the first button, create a macro that casts pyroblast. For the second button, use the following macro:

/castsequence reset=target scorch,scorch,scorch,scorch,vickerisawesome
/castsequence [combat,exists,harm,nodead] reset=12/target ,scorch,,frostfire bolt,,frostfire bolt,,frostfire bolt,,frostfire bolt,,frostfire bolt,,frostfire bolt
/cast living bomb

What this does:
The first cast sequence will apply four stacks of scorch and then get stuck where it says "vickerisawesome". You can replace "vickerisawesome" with any random word that isn't the name of a spell. The nonsense word is there to get the cast sequence to get stuck and not go back to the beginning.

Once the first cast sequence gets stuck, it goes on to the main rotation. Every 25 seconds or so, it will reapply scorch. At each of the double commas, the macro tries to cast living bomb. If living bomb is up already, it won't cast living bomb and the cast sequence moves on to the next frostfire bolt. The beauty of this is that if you try to cast living bomb on a target that already has your bomb on it, you get an error message of, "a more powerful spell is already active," and the spell doesn't cast, so the macro can move on and cast another frostfire bolt.

Summery:
Casts 4 stacks of scorch,
then applies living bomb,
then spams frostfire bolt.
Reapplies scorch before the stacks wears off.
Reapplies living bomb as soon as the previous living bomb has exploded.

When hot streak procs, use the other macro to cast a pyroblast.

I suggest using the addon "Power Auras" on your lead character. You can set this addon to pop up a warning on your lead character's screen whenever your mage has a hot streak buff.

You know the "official" way to stop a macro line from casting further? Use "Null," I learned that the other day =)