Here is a writeup i did on this when i replaced my cluster.

This is for removing the old cluster.
http://public.carnet.hr/~kpuljic/honda/cluster/

This is for installing the new cluster.
http://public.carnet.hr/~kpuljic/honda/new_cluster

The round-square thing Exempt was talking about is only an issue if you are installing 90-91 cluster in 88-89 civic, or 88-89 cluster in 90-91 civic. 88-89 clusters were more squarish and 90-91 are round. So if you're saying you're installing a cluster from 91 into 90 - you should have no problems.

Notice i had some more problems when installing the cluster since i had to repin connectors because i was installing EDM cluster into USDM civic. You most likely won't have such problems.