My colleagues and I developed two measures to assess attitudes toward homosexuality, the Homosexuality Attitude Scale and the Component Measure of Attitudes Toward Homosexuality. Either can be modified to assess attitudes toward gay men or lesbians by changing the statements within the measure.
The component measure is a multi-dimensional measure of attitudes toward homosexuality and includes four factors: Condemnation/Tolerance, Morality, Contact, and Stereotypes. Although the Condemnation/Tolerance and Morality factors may be similar for many purposes, it appears that the Contact and Stereotypes subscales are distinct factors. Researchers searching for a more fine-grained analysis of attitudes toward gay men and lesbians might choose one of those four factors.
The Homosexuality Attitude Scale (HAS) is a 21-item Likert scale that assesses people's stereotypes, misconceptions, and anxieties about homosexuals. The measure contains a unidimensional factor representing a favorable or unfavorable evaluation of anti-gay prejudice.
Researchers who wish to use the Homosexuality Attitude Scale (Kite & Deaux, 1986) or the Component Measure (LaMar & Kite, 1998) may do so as long as the reference for these measures is reported in any published document.
For more detailed information about the measures see:
Kite, M. E. & Deaux, K. (1986). Attitudes toward homosexuality: Assessment and behavioral consequences. Basic and Applied Social Psychology, 7, 137‑162. doi:10.1207/s15324834basp0702_4
LaMar, L. & Kite, M. E. (1998). Sex differences in attitudes toward gay men and lesbians: A multi-dimensional perspective. The Journal of Sex Research, 35, 189-196. doi:10.1080/00224499809551932