Connecting two desktop switches with more than one cable?

An unmanaged switch won't have the feature you're looking for and connecting two ports between both switches will create a switch loop, which will effectively render the switches and the network unusable.

A managed switch should have the feature that you're looking for, which is called Link Aggregation (LAG). Before purchasing a managed switch make sure to verify that it does indeed support LAG.

Yes, you can do this, if both switches support link aggregation (which goes by a variety of names such as bonding, NIC teaming, port trunking, etc.). You're unlikely to find this feature in consumer grade hardware or unmanaged switch.

The answer to the question you referred to even specifically mentioned LACP, one common protocol for link aggregation.

The open source router firmware DD-WRT appears to support link aggregation; if you're lucky enough to have bought hardware compatible with it then you could re flash the OEM firmware to DD-WRT to gain the feature.

Be warned that doing so is warranty voiding; and if something goes wrong you can brick your hardware so caveat emptor. Doing this will also require you to learn a new admin interface that's (of necessity) more complex than most consumer grade devices because it exposes so many more options, and reprogram any custom settings/rules you had in the hardware before switching it over.

However this is probably just a stopgap even if it works; while DD-WRT can give you a lot of the advanced features normally only available with enterprise networking hardware the chips controlling it are still only consumer grade and generally have significantly lower performance caps.