Specializing slot-value-using-class in OpenMCL

I am trying to add custom behavior to slot access by specializing
slot-value-using-class. Specifically, I want to add classes whose slot
values have been modified to a list of "dirty" classes. My code works
properly on SBCL but I run into problems on OpenMCL.

As mentioned elsewhere, OpenMCL optimizes away slot-value-using-class
within let forms[1]. I wasn't able to find any information about
turning off this optimization. Lispworks provides
':optimize-slot-access' option in class definition, is there something
similar in OpenMCL?

Elephant seems to support OpenMCL, so there must be a way to do
this. Unfortunately it seems that information is rather scarce.

[1] Curiously, this seems to work when the accessed slot symbol is in
a different package. However, variables declared as special in the let
form can't seem to be accessed from the specialized version of
slot-value-using-class.

--
Regards,
Slava Akhmechet.
.