It depends. Are you trying to put the pcolor in the same axes or in different axes. Starting in R2014b, MATLAB has a separate colormap for each axes, so the second case becomes pretty easy.
If you've got the first case (where they're in the same axes) things aren't as simple. If you've got R2014b or R2015a, then you can create two axes and overlay them. It would look a bit like the following:
ax1 = axes;
[x,y,z] = peaks;
ax2 = axes;
ax2.Visible = 'off';
ax2.XTick = ;
ax2.YTick = ;
set([ax1,ax2],'Position',[.17 .11 .685 .815]);
cb1 = colorbar(ax1,'Position',[.05 .11 .0675 .815]);
cb2 = colorbar(ax2,'Position',[.88 .11 .0675 .815]);
As you can see, the messiest part of that is that you don't get automatic layout with two colorbars. That means that you need to position them yourself.
If you're using an earlier version of MATLAB, then things are a little harder. There are a couple of file exchange utilties for combining two colormaps and then offseting the CData of one of your objects. That's probably the approach you'd have to take.