I've learned there are a couple of ways to do this, one using NetInfo Manager and the other using the CLI, the NetInfo route is a bit more reliable and hands free on OS X, in my opinion.
Before you start you may want to confirm that your Solaris box is actually exporting correctly or that it is set up to export to your IP space. From the CLI type:
showmount -e
www.yourNfsServer.com (or the IP address of the nfs server)
this will sow you a list of volumes and what IPs they are exporting to.
1) open NetInfo Mgr.
2) authenticate
3) select the mounts directory
4) click on the the "add new directory' icon and type Cmd+n
5) Using the Directory menu add the following properties and values to the ne entry
Property.....................Value
------------------------------------------------
name ........................ myNfsServer:/mydir/
type .......................... nfs
dir ............................. /the/mount/point/of/the/shared/volume/
6) Cmd + s to save or File>Save
7) Deauthenitcate
8) Try loggin out to incorporate these changes, but I have always had to Restart