Long story short, I decided to use a trainer for this (this being The Guild).
So far as I know, there are only two available- one has five options, the other about fourteen.

I can't get either to work.

The five-option one needs you to press numbers to get it to work, but I read somewhere you have to alt-tab to do it; except I can't alt-tab.
The fourteen-option one (which is available on some base10 site or something that doesn't actually have a working download link any more) needs to have ctrl+alt+___ to work. Pressing any combination of these does nothing- in fact, all pressing ctrl does is bring up the names of the stalls in the market.

I have tried everything I can to get these things to work, and nothing is, at all.

I realise most people here might not agree with cheating or whatever, but I don't know where else to go. Can anyone tell me what it is I need to do, please?

I don't know if you still care after all this time, but in the game's main configuration file (I don't remember exactly what it's named) there's a setting that says "=FULLSCREEN" If you change that to "=DIRECTWINDOW" you can run the game in a window so you can switch freely to the desktop or other programs.