Centering two figures on a page

[Matthias Weber <matweber@indiana.edu>]

Hello,

I have a bunch of figures of the same dimension 3.5x3.5.
On each page in a document, I'd like to place a pair of them \ so that
-- the figures are exactly  at the same location on each page
-- there is a specific horizontal gap between the figures
-- they are vertically aligned.

In short, I'd be happy if I could force TeX to put the left upper corner
of a figure at a specific location on the page.

All figures have the same dimension. I tried to improve on

\placefigure
	[nonumber,fit]
	[fig:page7]
	{Pair No 7}
	\framed{
		\startcombination[2*1]
			{\externalfigure[left7][width=3.5in]}{}
			{\externalfigure[right7][width=3.5in]}{}
	 	\stopcombination
	}

but I have no clue how to make the whitespace between the figures
to be say exactly .2 in, nor how to force a position of the float into  
the center of the page.

Details.pdf contains lots of suggestions for placements, and I have
the suspicion that I just haven't found it there yet -- maybe somebody 
here
can help me?

Thanks in advance for any help.

Matthias