There is a fairly recent (2012) book on the subject by John Tuel, though there are no reviews on Amazon so I have no idea how good it may be. The 1859 rules set by Bruce Weigle has a comprehensive list of sources, with comments on the content, and would seem to be a good starting point, having much historical information as well as the detailed rules themselves, which are geared towards use with 6mm - 15mm figures.
You might also consider reading the novel Radetzky's March by Joseph Roth, which begins with a brief account of Solferino, though its main focus is on the period following this, up to the end of the Habsburg empire in 1918, through the experiences of three generations of a single family.