Heya,
Are you referring to running that same 266FSB 1Ghz Thunderbird CPU? If so, that CPU ships locked at a 7.5 multiplier (1 Ghz = 7.5 x 133).
If you put that CPU into a 200FSB motherboard like you suggest, Scrap Silicon is correct, the board will recognize the CPU's 7.5 multiplier and run it at the default 200 Mhz FSB, yielding a performance decrease for your CPU as if it were a 750 Mhz CPU (750 Mhz = 7.5 x 100).
In order to get around this, yes, you would have to "connect the dots" as you write, the L1 briges. Alternately, you could just increment the FSB speed from 100 Mhz (200Mhz DDR) to 110 Mhz (220 Mhz DDR) or so, which will also yield a noticable performance gain. A mild 10% overclock like this should not adversely affect the stability of your PCI and IDE devices.
Nevertheless, a 10% overclock will not return that 1 Ghz CPU running at 750 Mhz to 1 Ghz performance (750Mhz x 1.1 = 825 Mhz). Best thing to do is order a CPU designed for your board.
I don't recommend connecting the L1 bridges for those not used to soldering, as the chances of ruining the CPU are high, which would kill your ability to RMA the CPU. Many novices try the safer pencil-graphite stick method instead, but this is also not recommended as graphite connections do not last, they must be reapplied, and the last thing you want to do is remove your heatsink every 6-12 months and reapply graphite.
L8r,
PCM