In absense of any other answers thus far... I don't have the PSR-500, but I don't see why these values should be any different than normal. If the hi/lo values that you are looking for are frequencies, just get them out of the database here. If thay are the channel number values (ie, 380 and up), then I can check my database and/or just run the system through UniTrunker when I get home this evening.
I would try 380 as low and 579 as high. I think that's pretty standard with a single table. I know it's worked with other UHF motorola systems on the 500.