However you still have to capture the data on the PC end, which will involve either writing a custom utility, or some very gnarly VBA scripting in Excel (Microchip don't make it easy to access legacy ports), or using the AACkeys accessibility utility, and make your widget's firmware output GIDEI commands and data keystrokes to type your data directly into Excel (though its probably safer to open a new Notepad with:
I'd recommend writing a simple application to receive, timestamp (unless the temperature scanner timestamps the data already), and record the data on the host PC. You'll be able to do this in practically any programming language you so desire.
I'd avoid using anything like GIDEI (unless you *really* want to do that as a learning experience). Instead, I'd just define a very simple arbitrary format for streaming the measurement data (and any metadata, like a rolling unsigned 32-bit scan counter, etc) from your temperature scanner device to the host PC. There are plenty of measurement instruments out there that do this kind of thing already to draw inspiration from.
If you record the measurement data using a simple and widely-supported file format (e.g., Comma-Separated Value file, etc), then you'll likely be able to import/use the recorded data easily with a range of applications and tools (e.g., Excel, Matlab, gnuplot, etc). If you want to 'beatify' and plot this data in Excel, then you can write some simple VBA macros to pull in the data and do whatever you require within an Excel workbook.
Not only will this approach meet the basic requirements stated, you'll also end up with a solution that provides a greater degree of flexibility without much to any additional effort. I'd even wager this approach is more simple and less error prone.