Found it! It's the April 1992 issue on STIV. There's also a retrospective on the previous movies. Here's what Walter Koenig had to say in Mark Altman's article:
Koenig said he nearly passed on doing the film a bitter dispute with producer Harve Bennett. "Chekov was virtually nonexistent," noted Koenig. "I wasn't expecting that after STAR TREK II. Bennett asked me to see him after I read the script in his office, but my agent had to go because he had appointments and asked me if I minded leaving also. Since I was disappointed with the script anyway, I said okay. Bennett took inordinate umbrage that I did not come by his office and called up my agent and chewed him out. He said I had the worst Russian accent in Hollywood and if it were not for STAR TREK, I would never work and went on at great length, totally denigrating me, not to my face, but to my agent. I then received what I was told was a final offer to do the movie, a take it or leave it offer, and I demurred. It wasn't easy. I'm not such a strong character by nature, but I was angry at being so undeservedly demeaned by him. I thought that was the end of it, that I was no longer going to be in STAR TREK. I told them I was not going to accept the offer they gave me. I went home and told my family there was not going to be any more STAR TREK in out lives. Interestingly enough, they came back the next day with just enough more for me to be able to save face and accept it. I would not have called back and said I changed my mind. That set the tone for STAR TREK III."
According to Koenig, however, the biggest failing of STAR TREK III--discounting his lack of lines--was his outfit, a pink jumpsuit with a white collar. "I thought it was ridiculous looking, " said Koenig. "Robert Fletcher patterned it after some Russian artist who dressed that way, with a little dicky and everything. We had shot some footage with it and Michael Eisner [then head at Paramount] looked at the dailies and said he didn't like it. Leonard came up and said, 'We're going to take you out of the costume,' And I said, 'Thank God.' Leonard replied, 'Why didn't you say something?' and was a little bit irritated. I thought, 'Why the hell didn't I say something?' I was just so into this mindset that I was just the hired help and had no input. It never occurred to me that I might say, 'I don't like this.'"
So yeah, it doesn't sound like he had a very good time on that movie.
I also found a neat costuming tidbit in a 1987 issue: When they were doing STIII, they wanted to reuse the 12 Klingon outfits that had been made for TMP, but 6 of them were in very bad shape because they'd been used and altered for an episode of Mork & Mindy. The other six had been used in convention appearances and were also rather worn.