I've been giving this some thought (This is proably the sort of thing that could be sorted in five minutes if you lived next door).
DEVC++ should be able to use *.li and *.a type libraries.
But I've just had a thought - is there a library called libmysqlclient.a in your C:\Program Files\MySQL\MySQL Server 5.0\lib\opt directory?
(there is in mine).
If so try linking with that instead and see what happens.