Exposure of "direct" arrays

Under CMUCL, there is functionality to make an array accessed by a C
program and CL have the "same data" by getting the address of the
array from CMUCL.  This is obviously risky (the manual suggests you
should turn off garbage collection when you do this to avoid your
thing getting moved out from udner you, for instance), but I'm finding
that at this point, a substantialy fraction of my total runtime (maybe
20%) is spend basically copying my data between my CMUCL array and the
foreign array which is passed to C.  So is this functionality exposed
at all in UFFI, or do I have to switch to using CMUCL's FFI directly
in order to get at it?

rif