You can’t. Read the sticky.
You can try to workaround this limitation with a castsequence, but it is not likely to work well - I expect in practice you will wind up with Elemental Blast available but still only able to cast Lightning Bolt because the sequence didn’t reset properly, or the alternative where the sequence resets early and you are stuck on Elemental Blast while it is on cooldown and unable to cast Lightning Bolt.
A better option is to use modifier macros, like so:
#showtooltip
/use [mod:ctrl]Elemental Blast;Lightning Bolt