.TS
tab(@);
l c l.
A cell @.PSPIC mypic.ps @Another cell
.TE
tbl runs first and processes its data as words of text --
it has no concept of macros. One way to achieve what you
want is to pass this on to the general troff machinery,
which happens in paragraph mode of tbl:
.TS
allbox tab(@);
c c c.
Foo@T{
\h'1c'
.sp -1
.PSPIC -L image.ps 1c
T}@bar
.TE
Note that PSPIC is intended to include graphics between lines
of text, so it will leave some vertical space above and below,
and it also does not have any intrinsic width, so you must
put in some dummy material that has the desired extent
(in the example, horizontal motion)
However, PSPIC is built around the "ps: import" device escape,
which you can use directly. This also has no concept of
width and height with regard to troff's text formatting (and
will happily overwrite anything on the page), so you need to
supply some dummy material for tbl to leave appropriate space.
But it has the advantage that you can tweak the vertical
positioning simply by lying about the bounding box, like in
the attached example.