Instead of "hard" (in-process) linking which is segfault prone and hard to do right the first time, I would suggest splitting the Perl job into a separate process. There are at least two ways to do this:

• Write your spreadsheet formatter as a separate Perl program and feed it data through standard input (see perldoc perlopentut or the IPC modules). You need too define an unobfuscated data representation format ; XML might help.
• Make your Pascal program write code "on the fly" into a string, and then feed it to the Perl interpreter. This might be easier to prototype, but less consistent and harder to debug.

Update: braino - Perl code is the callee, not the caller, so the doc pointers are not immediately relevant. Good material for reading, though.