Here's some ideas I've come up with after thinking for a while:
Add three vars to the chat options: 'name', 'type' and 'get'. Name would be what's shown in the config form next to the control widget, type controls which widget to use, and get is a function (or closure) to retrieve the current value (to load settings when the client starts). We can use the already defined 'desc' to make tooltips. We could have the following types:
"bool": boolean values, use a check box.
"string": string value, passed directly to the function given in 'method' (which we already have defined in the chat options), use a textbox, maybe with a small button next to it to send the message
"func": execute a command, use a button.
"rangespin": number, using a spinbox (you know, a small textbox with two arrows to increment and decrement the value)
"rangeslide": same as previous, using a slider. Maybe add another var to define value limits for these two?
For chat options that already have an args-table, use a drop-down menu or combobox (what's the difference between those two anyways? =P). Or maybe there are cases where radio buttons would work better? You/we'll have to research that.
There are probably more widget types we can use too, but these are what I've thought of so far. I'm sure you've thought of much of this yourself, already. I just had to write this down, because I like this project so much =) It's like I'm wondering why noone has done this yet.
Oh, and one last thing: How about merging with AceCommander, and use that to config old mods that haven't been set up for this mod?