Lamprey is easier than Shoggoth, just learn the pin spots (one at E10, one northish by the fork). And ya, that's how to do Shoggy.
For PDT/MDT, I have a "PDEFNeeded" or "MDEFNeeded" variable which is set to 1 in a macro which also executes Meteor (a "dummy" spell which I tell Spellcast not to process any gear for); Spellcast will abort the changes associated with a previous spell when another is cast.
The macro looks like
/console sc var set PDEFNeeded 1
/ma "Meteor" <t>
/echo PDEF equipped!
And then in SC
Code:
<if advanced='$PDEFNeeded == 1'>
<equip when="precast" set="PDEF" />
<var cmd="set PDEFNeeded 0" />
</if>