You can use a standalone utility or third-party software to convert EML files to PST format without using Outlook. Some options you can consider are:

Microsoft Exchange Server Import and Export Tool: This is a free tool from Microsoft that you can use to import EML files into Outlook. You can use this tool to import EML files into an existing PST file or create a new PST file.

EML to PST Converter: Several third-party utilities available can convert EML files to PST format. These tools usually have a simple user interface that permits you to convert multiple EML files simultaneously.

Online EML to PST Converter: Several online tools are available that allow you to convert EML to PST format without installing any software on your computer. These tools are usually free to use, and you can access them from any device with an internet connection.

Before using any of these tools, make sure to read reviews and do your research to find a reliable and trustworthy solution.