I would have a look here:
http://www.frontrank.com/2_lev2_Napoleonic.asp
They appear to be the later 1815 uniform
The advent of Perry and/or Victrix plastic figures could make conversion quite easy. The line infantry uniform is very similar to the French 1815 look, with only the junction between turnbacks and lapels being different. The shako details could be carefully shaved off the front and repositioned at the side, or replaced with greenstuff detailing. Not to hard or complicated. Aagin, the Grenadiers are very similar to French line Grenadiers, but you'd need to get some earlier bearskinn heads and model a different shape to the plate at the front. Considering you'd only need maybe 10 or 12 figures, not an unreasonable task.
I have the "Napoleonic Uniforms" books by J Elting, illustrated by Knotel. There is quite a decent section on the early Netherlands forces which should give you enough uniform detail to work with.
PM me on Friday and I'll try and scan some of the pics in and e-mail them.
I'll be going away in an hour or so, or I'd do it today