do you have any command line interface to run sql statements on your solaris system? If not, google says: http://www.sommarskog.se/mssqlperl/unix.html
If so, then you could create a sequential file within a baan program. Write the required sql-statements to this file. Call the command line interface to process this file with the shell() command from within the baan program. If you redirect the output of the sql-program to a file, you can again read the results within the baan program.
Not sure on the second part of your question ... if Baan is using oracle8i, what is the problem in writing there? If you want to write to tables not known to the Baan system, use the above method via seq. files.