Hello,
I've just found a useful thread for locks on the wow forums and thought I'd post it here. This provides some interesting tips that aren't commonly found in other lock raiding guides.
http://forums.worldofwarcraft.com/threa ... 6289&sid=1
Of particular note (if you're destro spec) is the paragraph below concerning imp casts.:
"Well there is one serious issue with destro, and that is that the imp does not use the spell queue system. For those that don't know when you cast a spell with a cast time > 1second if you hit another spell in the last .5seconds of the cast it queues it up on the server to be immediately cast next so there is no downtime. The imp does not do this on autoattack however so you want to macro his cast to your spells. For example even though the imps Fire Bolt cast is a 2.0second cast he only casts it every 2.4 seconds. The following macro will fix this."
#showtooltip Incinerate
/cast [pet:imp] Fire Bolt
/cast Incinerate