You're looking at the wrong tool. Storable serialises Perl data structures. Even if a C-callable Storable library existed, you'd have to convert your C-structure into a Perl data structure first before you could use it.

Most relative simple C-structs--ie. those that do not contain pointers--are most easily and efficiently accessed from Perl using unpack. If the structure uses pointers, then serialising it to some text format, is probably far easier than converting it to Perl's internal format.