I have replaced the timing belt + the accessories belts in my Volvo 240 wagon (1990).
Long story short, all the complication is around getting the accessories belt loose.
Key for that, understanding than the tensioning mechanism includes 2 bolts, one that presses the real release bolt that is in the back, and one that release and tight the belts that is always on the top.
My 2 cents: If it is not your only one car, take some days to do this. You can do one day all the belts loosing, then another day the time belt replacement and finally a third day for reinstalling everything.
Regards, Nacho.
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