I just wanted to report that I have successfully flashed Tomato onto a Linksys WRT150N v1 and it's working nicely. Tomato reports it as a WRT300N, but that doesn't matter.
The method I used was to go from Linksys stock firmware to DD-WRT K24 (dd-wrt.v24-12548_NEWD_mini.bin) to Tomato K24 (tomato-ND-1.28.7633.3-Toastman-IPT-ND-Std.trx).
This should work for WRT150N v1, WRT150N v1.1, WRT160N v1 and WRT300N v1. They all use the same chipset.
Whatever you do, do not flash with a K26 version of Tomato or DD-WRT. This will brick it.