I imagine that it’s a well trodden path seeking out a satisfactory code or syntax highlighter for wordpress.
You can, just about, paste colour-formatted code from some editors into the wp text editor (e.g. SSMS to Outlook Email to WordPress), but it creates a mess of the HTML. Not pretty at all.
- Crayon Syntax Highlighter. Nice to use; line numbers; expansion to new window; code-block size limits. The main drawback seems to be that the colouring is rather random.