I've become interested in this problem as well, of late. Looks like gardening may be in the future for a lot of us if food prices follow the cost of fuel.
For prepping the soil or working in mulch/manure, I imagine a 3PH rototiller or a disc harrow would be quite useful. 4 ft. sizes are available for the
B7610. King Kutter makes the XB series tiller which is sized for BX and B series machines. But the tiller goes for over $1K, as I recall, while the disk harrows were around $650. Maybe a small subsoiler/middlebuster would be an economical alternative...they go for around $200. Don't think they'd work nearly as well as a tiller though.
But, once the garden's planted, the tiller and disc harrow won't be of much use. I've seen a single row 3PH cultivator offered by Howse. It's got 6 tines (3 on each side) and would probably do a good job of turning up soil between the rows if your spacing let you straddle the row. They were around $220 a year or so ago. Would probably last forever in the typical garden.
For planting there are small 2-row 3PH corn planters, but the one my Dad used to have was too big for the
B7610. It was the perfect size for a Ford 8N tractor. I've heard of single row, push powered seed drills for planting garden crops, but haven't seen anything similar offered for a small CUT. Maybe garden seeding is something better done by hand anyway.
I'll be watching the responses to this thread. There are some serious gardeners who post here. I've never put in a garden and am just starting to read up on the subject.
Bob